cake collapse is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-11-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
After lyophilization, the product is usually a porous cake or powder with a large internal surface area. This structure can absorb moisture quickly if exposed to humid air, so vials are sealed under vacuum or an inert gas. Moisture uptake may lower the glass transition temperature of the dried matrix and accelerate chemical or physical degradation. Storage conditions therefore depend on the formulation, container, and intended shelf life. Some products remain stable at room temperature, while others require refrigeration or freezing.
Quality control for lyophilized products includes appearance, cake structure, reconstitution time, pH, residual moisture, and potency. Residual moisture is a key attribute because excess water can reduce stability, while excessively low moisture may cause structural changes or aggregation in some systems. Stability studies compare real-time and accelerated conditions to estimate shelf life. Analytical methods must be validated for the specific matrix, container, and moisture range. Sterility and container integrity are also monitored for sterile products.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
| Property | Value | Notes |
|---|---|---|
| Typical appearance | White to off-white porous cake or powder | Color and structure vary with formulation. |
| Typical reconstitution time | Seconds to several minutes | Diluent, agitation, and temperature affect rate. |
| Typical storage temperature | 2–8 °C, 15–25 °C, or ≤−20 °C | Product-specific; protect from moisture and light. |
| Typical container closure | Glass vial with rubber stopper and crimp seal | Closure must limit moisture ingress. |
| Typical stability indicator | Residual moisture, potency, and reconstitution time | Monitored throughout shelf life. |
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
Misconceptions about lyophilization include the idea that dried products are indefinitely stable or that vacuum sealing eliminates all degradation. Chemical reactions can continue in the solid state, and some proteins lose activity even at low moisture. Another misconception is that any freeze-dryer cycle can be scaled by time alone; heat and mass transfer differ with equipment and load. Open questions remain about predicting long-term stability from short accelerated studies, particularly for amorphous formulations. Real-time stability data remain the standard for shelf-life assignment.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
=== Recipient's selection of donors === Sperm banks make information available about the sperm donors whose donations they hold to enable customers to select the donor whose sperm they wish to use. This information is often available by way of an online catalog. Subscription fees to be able to view the sperm donor through California Cryobank, for example, start at $145. Information made available by a sperm bank will usually include the race, height, weight, blood group, health and eye color of the donor. Sometimes information about the donor's age, family history and educational achievements will also be given. Some sperm banks make a 'personal profile' of a donor available and occasionally more information may be purchased about a donor, either in the form of a DVD or in written form. Catalogs usually state whether samples supplied by a particular donor have already given rise to pregnancies, but this is not necessarily a guide to the fecundity of the sperm since a donor may not have been in the program long enough for any pregnancies to have been recorded. The donor's educational qualification is also taken into account when choosing a donor.
=== EC 2.1.1: Methyltransferases === EC 2.1.1.1: nicotinamide N-methyltransferase EC 2.1.1.2: guanidinoacetate N-methyltransferase EC 2.1.1.3: thetin—homocysteine S-methyltransferase EC 2.1.1.4: acetylserotonin O-methyltransferase EC 2.1.1.5: betaine—homocysteine S-methyltransferase EC 2.1.1.6: catechol O-methyltransferase EC 2.1.1.7: nicotinate N-methyltransferase EC 2.1.1.8: histamine N-methyltransferase EC 2.1.1.9: thiol S-methyltransferase EC 2.1.1.10: homocysteine S-methyltransferase EC 2.1.1.11: magnesium protoporphyrin IX methyltransferase EC 2.1.1.12: methionine S-methyltransferase EC 2.1.1.13: methionine synthase EC 2.1.1.14: 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase EC 2.1.1.15: fatty-acid O-methyltransferase EC 2.1.1.16: methylene-fatty-acyl-phospholipid synthase EC 2.1.1.17: phosphatidylethanolamine N-methyltransferase EC 2.1.1.18: polysaccharide O-methyltransferase EC 2.1.1.19: trimethylsulfonium—tetrahydrofolate N-methyltransferase EC 2.1.1.20: glycine N-methyltransferase EC 2.1.1.21: methylamine—glutamate N-methyltransferase EC 2.1.1.22: carnosine N-methyltransferase EC 2.1.1.23: now covered by EC 2.1.1.124, EC 2.1.1.125 and EC 2.1.1.126 EC 2.1.1.24: now covered by EC 2.1.1.77, EC 2.1.1.80 and EC 2.1.1.100 EC 2.1.1.25: phenol O-methyltransferase EC 2.1.1.26: iodophenol O-methyltransferase EC 2.1.1.27: tyramine N-methyltransferase EC 2.1.1.28: phenylethanolamine N-methyltransferase EC 2.1.1.29: Now covered by EC 2.1.1.202, EC 2.1.1.203 and EC .1.1.204 EC 2.1.1.30: tRNA (purine-2- or -6-)-methyltransferase: Reactions previously described are due to EC 2.1.1.32 EC 2.1.1.31: Now covered by EC 2.1.1.221 and EC 2.1.1.228 EC 2.1.1.32: Now covered by EC 2.1.1.213, EC 2.1.1.214, EC 2.1.1.215 and EC 2.1.1.216 EC 2.1.1.33: tRNA (guanine46-N7)-methyltransferase EC 2.1.1.34: tRNA (guanosine18-2′-O)-methyltransferase EC 2.1.1.35: tRNA (uracil54-C5)-methyltransferase EC 2.1.1.36: Now covered by EC 2.1.1.217, EC 2.1.1.218, EC 2.1.1.219, EC 2.1.1.220 EC 2.1.1.37: DNA (cytosine-5-)-methyltransferase EC 2.1.1.38: O-demethylpuromycin O-methyltransferase EC 2.1.1.39: inositol 3-methyltransferase EC 2.1.1.40: inositol 1-methyltransferase EC 2.1.1.41: sterol 24-C-methyltransferase EC 2.1.1.42: flavone 3′-O-methyltransferase EC 2.1.1.43: Now described by EC 2.1.1.354, EC 2.1.1.355, EC 2.1.1.356, EC 2.1.1.357, EC 2.1.1.358, EC 2.1.1.359, EC 2.1.1.360, EC 2.1.1.361 and EC 2.1.1.362 EC 2.1.1.44: L-histidine Nα-methyltransferase EC 2.1.1.45: thymidylate synthase EC 2.1.1.46: isoflavone 4′-O-methyltransferase EC 2.1.1.47: indolepyruvate C-methyltransferase EC 2.1.1.48: Now covered by EC 2.1.1.181, EC 2.1.1.182, EC 2.1.1.183 and EC 2.1.1.184 EC 2.1.1.49: amine N-methyltransferase EC 2.1.1.50: loganate O-methyltransferase EC 2.1.1.51: Now covered by EC 2.1.1.187 and EC 2.1.1.188 EC 2.1.1.52: Now covered by EC 2.1.1.171, EC 2.1.1.172, EC 2.1.1.173 and EC 2.1.1.174 EC 2.1.1.53: putrescine N-methyltransferase EC 2.1.1.54: deoxycytidylate C-methyltransferase EC 2.1.1.55: tRNA (adenine-N6-)-methyltransferase EC 2.1.1.56: mRNA (guanine-N7)-methyltransferase EC 2.1.1.57: methyltransferase cap1 EC 2.1.1.58: deleted, included in EC 2.1.1.57 EC 2.1.1.59: [cytochrome c]-lysine N-methyltransferase EC 2.1.1.60: calmodulin-lysine N-methyltransferase EC 2.1.1.61: tRNA (5-methylaminomethyl-2-thiouridylate)-methyltransferase EC 2.1.1.62: mRNA (2′-O-methyladenosine-N6-)-methyltransferase EC 2.1.1.63: methylated-DNA—[protein]-cysteine S-methyltransferase EC 2.1.1.64: 3-demethylubiquinol 3-O-methyltransferase EC 2.1.1.65: licodione 2′-O-methyltransferase EC 2.1.1.66: Now covered by EC 2.1.1.230 EC 2.1.1.67: thiopurine S-methyltransferase EC 2.1.1.68: caffeate O-methyltransferase EC 2.1.1.69: 5-hydroxyfuranocoumarin 5-O-methyltransferase EC 2.1.1.70: 8-hydroxyfuranocoumarin 8-O-methyltransferase EC 2.1.1.71: phosphatidyl-N-methylethanolamine N-methyltransferase EC 2.1.1.72: site-specific DNA-methyltransferase (adenine-specific) EC 2.1.1.73: deleted: reaction is that of EC 2.1.1.37, DNA (cytosine-5-)-methyltransferase EC 2.1.1.74: methylenetetrahydrofolate—tRNA-(uracil54-C5)-methyltransferase [NAD(P)H-oxidizing] EC 2.1.1.75: apigenin 4′-O-methyltransferase EC 2.1.1.76: quercetin 3-O-methyltransferase EC 2.1.1.77: protein-L-isoaspartate(D-aspartate) O-methyltransferase EC 2.1.1.78: isoorientin 3′-O-methyltransferase EC 2.1.1.79: cyclopropane-fatty-acyl-phospholipid synthase EC 2.1.1.80: protein-glutamate O-methyltransferase EC 2.1.1.81: deleted, included in EC 2.1.1.49 EC 2.1.1.82: 3-methylquercetin 7-O-methyltransferase EC 2.1.1.83: 3,7-dimethylquercetin 4′-O-methyltransferase EC 2.1.1.84: methylquercetagetin 6-O-methyltransferase EC 2.1.1.85: protein-histidine N-methyltransferase EC 2.1.1.86: Now covered by EC 7.2.1.4 EC 2.1.1.87: pyridine N-methyltransferase EC 2.1.1.88: 8-hydroxyquercetin 8-O-methyltransferase EC 2.1.1.89: tetrahydrocolumbamine 2-O-methyltransferase EC 2.1.1.90: methanol—5-hydroxybenzimidazolylcobamide Co-methyltransferase EC 2.1.1.91: isobutyraldoxime O-methyltransferase EC 2.1.1.92: Now included with EC 2.1.1.69 EC 2.1.1.93: is identical to EC 2.1.1.70, 8-hydroxyfuranocoumarin 8-O-methyltransferase EC 2.1.1.94: tabersonine 16-O-methyltransferase EC 2.1.1.95: tocopherol C-methyltransferase EC 2.1.1.96: thioether S-methyltransferase EC 2.1.1.97: 3-hydroxyanthranilate 4-C-methyltransferase EC 2.1.1.98: diphthine synthase EC 2.1.1.99: 3-hydroxy-16-methoxy-2,3-dihydrotabersonine N-methyltransferase EC 2.1.1.100: protein-S-isoprenylcysteine O-methyltransferase EC 2.1.1.101: macrocin O-methyltransferase EC 2.1.1.102: demethylmacrocin O-methyltransferase EC 2.1.1.103: phosphoethanolamine N-methyltransferase EC 2.1.1.104: caffeoyl-CoA O-methyltransferase EC 2.1.1.105: N-benzoyl-4-hydroxyanthranilate 4-O-methyltransferase EC 2.1.1.106: tryptophan 2-C-methyltransferase EC 2.1.1.107: uroporphyrinogen-III C-methyltransferase EC 2.1.1.108: 6-hydroxymellein O-methyltransferase EC 2.1.1.109: demethylsterigmatocystin 6-O-methyltransferase EC 2.1.1.110: sterigmatocystin 8-O-methyltransferase EC 2.1.1.111: anthranilate N-methyltransferase EC 2.1.1.112: glucuronoxylan 4-O-methyltransferase EC 2.1.1.113: site-specific DNA-methyltransferase (cytosine-N4-specific) EC 2.1.1.114: polyprenyldihydroxybenzoate methyltransferase EC 2.1.1.115: (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline N-methyltransferase EC 2.1.1.116: 3′-hydroxy-N-methyl-(S)-coclaurine 4′-O-methyltransferase EC 2.1.1.117: (S)-scoulerine 9-O-methyltransferase EC 2.1.1.118: columbamine O-methyltransferase EC 2.1.1.119: 10-hydroxydihydrosanguinarine 10-O-methyltransferase EC 2.1.1.120: 12-hydroxydihydrochelirubine 12-O-methyltransferase EC 2.1.1.121: 6-O-methylnorlaudanosoline 5′-O-methyltransferase EC 2.1.1.122: (S)-tetrahydroprotoberberine N-methyltransferase EC 2.1.1.123: [cytochrome-c]-methionine S-methyltransferase EC 2.1.1.124: Now covered by EC 2.1.1.319, EC 2.1.1.320, EC 2.1.1.321 and EC 2.1.1.322 EC 2.1.1.125: Now covered by EC 2.1.1.319, EC 2.1.1.320 and EC 2.1.1.321 EC 2.1.1.126: Now covered by EC 2.1.1.319, EC 2.1.1.320 and EC 2.1.1.321 EC 2.1.1.127: [ribulose-bisphosphate carboxylase]-lysine N-methyltransferase EC 2.1.1.128: (RS)-norcoclaurine 6-O-methyltransferase EC 2.1.1.129: inositol 4-methyltransferase EC 2.1.1.130: precorrin-2 C20-methyltransferase EC 2.1.1.131: precorrin-2 C17-methyltransferase EC 2.1.1.132: precorrin-6B C5,15-methyltransferase (decarboxylating) EC 2.1.1.133: precorrin-4 C11-methyltransferase EC 2.1.1.134: now with EC 2.1.1.129 EC 2.1.1.135: now EC 1.16.1.8 EC 2.1.1.136: chlorophenol O-methyltransferase EC 2.1.1.137: arsenite methyltransferase EC 2.1.1.138: deleted: Reaction due to EC 2.1.1.137 EC 2.1.1.139: 3′-demethylstaurosporine O-methyltransferase EC 2.1.1.140: (S)-coclaurine-N-methyltransferase EC 2.1.1.141: jasmonate O-methyltransferase EC 2.1.1.142: cycloartenol 24-C-methyltransferase EC 2.1.1.143: 24-methylenesterol C-methyltransferase EC 2.1.1.144: trans-aconitate 2-methyltransferase EC 2.1.1.145: trans-aconitate 3-methyltransferase EC 2.1.1.146: (iso)eugenol O-methyltransferase EC 2.1.1.147: corydaline synthase EC 2.1.1.148: thymidylate synthase (FAD) EC 2.1.1.149: Now covered by EC 2.1.1.267, flavonoid 3′,5′-methyltransferase EC 2.1.1.150: isoflavone 7-O-methyltransferase EC 2.1.1.151: cobalt-factor II C20-methyltransferase EC 2.1.1.152: precorrin-6A synthase (deacetylating) EC 2.1.1.153: vitexin 2′′-O-rhamnoside 7-O-methyltransferase EC 2.1.1.154: isoliquiritigenin 2′-O-methyltransferase EC 2.1.1.155: kaempferol 4′-O-methyltransferase EC 2.1.1.156: glycine/sarcosine N-methyltransferase EC 2.1.1.157: sarcosine/dimethylglycine N-methyltransferase EC 2.1.1.158: 7-methylxanthosine synthase EC 2.1.1.159: theobromine synthase EC 2.1.1.160: caffeine synthase EC 2.1.1.161: dimethylglycine N-methyltransferase EC 2.1.1.162: glycine/sarcosine/dimethylglycine N-methyltransferase EC 2.1.1.163: demethylmenaquinone methyltransferase EC 2.1.1.164: demethylrebeccamycin-D-glucose O-methyltransferase EC 2.1.1.165: methyl halide transferase EC 2.1.1.166: 23S rRNA (uridine2552-2′-O)-methyltransferase EC 2.1.1.167: 27S pre-rRNA (guanosine2922-2′-O)-methyltransferase EC 2.1.1.168: 21S rRNA (uridine2791-2′-O)-methyltransferase EC 2.1.1.169: tricetin 3′,4′,5′-O-trimethyltransferase EC 2.1.1.170: 16S rRNA (guanine527-N7)-methyltransferase EC 2.1.1.171: 16S rRNA (guanine966-N2)-methyltransferase EC 2.1.1.172: 16S rRNA (guanine1207-N2))-methyltransferase EC 2.1.1.173: 23S rRNA (guanine2445-N2)-methyltransferase EC 2.1.1.174: 23S rRNA (guanine1835-N2)-methyltransferase EC 2.1.1.175: tricin synthase EC 2.1.1.176: 16S rRNA (cytosine967-C5)-methyltransferase EC 2.1.1.177: 23S rRNA (pseudouridine1915-N3)-methyltransferase EC 2.1.1.178: 16S rRNA (cytosine1407-C5)-methyltransferase EC 2.1.1.179: 16S rRNA (guanine1405-N7)-methyltransferase EC 2.1.1.180: 16S rRNA (adenine1408-N1)-methyltransferase EC 2.1.1.181: 23S rRNA (adenine1618-N6)-methyltransferase EC 2.1.1.182: 16S rRNA (adenine1518-N6/adenineadenine1519-N6)-dimethyltransferase EC 2.1.1.183: 18S rRNA (adenine1779-N6/adenine1780-N6)-dimethyltransferase EC 2.1.1.184: 23S rRNA (adenine2085-N6)-dimethyltransferase EC 2.1.1.185: 23S rRNA (guanosine2251-2′-O)-methyltransferase EC 2.1.1.186: 23S rRNA (cytidine2498-2′-O)-methyltransferase EC 2.1.1.187: 23S rRNA (guanine745-N1)-methyltransferase EC 2.1.1.188: 23S rRNA (guanine748-N1)-methyltransferase EC 2.1.1.189: 23S rRNA (uracil747-C5)-methyltransferase EC 2.1.1.190: 23S rRNA (uracil1939-C5)-methyltransferase EC 2.1.1.191: 23S rRNA (cytosine1962-C5)-methyltransferase EC 2.1.1.192: 23S rRNA (adenine2503-C2)-methyltransferase EC 2.1.1.193: 16S rRNA (uracil1498-N3)-methyltransferase EC 2.1.1.194: A mixture of EC 2.1.1.192 and EC 2.1.1.224 EC 2.1.1.195: cobalt-precorrin-5B (C1)-methyltransferase EC 2.1.1.196: cobalt-precorrin-7 (C15)-methyltransferase (decarboxylating) EC 2.1.1.197: malonyl-[acyl-carrier protein] O-methyltransferase EC 2.1.1.198: 16S rRNA (cytidine1402-2′-O)-methyltransferase EC 2.1.1.199: 16S rRNA (cytosine1402-N4)-methyltransferase EC 2.1.1.200: tRNA (cytidine32/uridine32-2′-O)-methyltransferase EC 2.1.1.201: 2-methoxy-6-polyprenyl-1,4-benzoquinol methylase EC 2.1.1.202: multisite-specific tRNA:(cytosine-C5)-methyltransferase EC 2.1.1.203: tRNA (cytosine34-C5)-methyltransferase EC 2.1.1.204: tRNA (cytosine38-C5)-methyltransferase EC 2.1.1.205: tRNA (cytidine32/guanosine34-2′-O)-methyltransferase EC 2.1.1.206: tRNA (cytidine56-2′-O)-methyltransferase EC 2.1.1.207: tRNA (cytidine34-2′-O)-methyltransferase EC 2.1.1.208: 23S rRNA (uridine2479-2′-O)-methyltransferase EC 2.1.1.209: 23S rRNA (guanine2535-N1)-methyltransferase EC 2.1.1.210: demethylspheroidene O-methyltransferase EC 2.1.1.211: tRNASer(uridine44-2′-O)-methyltransferase EC 2.1.1.212: 2,7,4′-trihydroxyisoflavanone 4′-O-methyltransferase EC 2.1.1.213: tRNA (guanine110-N2)-dimethyltransferase EC 2.1.1.214: tRNA (guanine10-N2)-methyltransferase EC 2.1.1.215: tRNA (guanine26-N2/guanine27-N2)-dimethyltransferase EC 2.1.1.216: tRNA (guanine26-N2)-dimethyltransferase EC 2.1.1.217: tRNA (adenine22-N1)-methyltransferase EC 2.1.1.218: tRNA (adenine9-N1)-methyltransferase EC 2.1.1.219: tRNA (adenine57-N1/adenine58-N1)-methyltransferase EC 2.1.1.220: tRNA (adenine58-N1)-methyltransferase EC 2.1.1.221: tRNA (guanine9-N1)-methyltransferase EC 2.1.1.222: 2-polyprenyl-6-hydroxyphenyl methylase EC 2.1.1.223: tRNA1Val (adenine937-N6)-methyltransferase EC 2.1.1.224: 23S rRNA (adenine2503-C8)-methyltransferase EC 2.1.1.225: tRNA:m4X modification enzyme EC 2.1.1.226: 23S rRNA (cytidine1920-2′-O)-methyltransferase EC 2.1.1.227: 16S rRNA (cytidine1409-2′-O)-methyltransferase EC 2.1.1.228: tRNA (guanine37-N1)-methyltransferase EC 2.1.1.229: tRNA (carboxymethyluridine34-5-O)-methyltransferase EC 2.1.1.230: 23S rRNA (adenosine1067-2′-O)-methyltransferase EC 2.1.1.231: flavonoid 4′-O-methyltransferase EC 2.1.1.232: naringenin 7-O-methyltransferase EC 2.1.1.233: [phosphatase 2A protein]-leucine-carboxy methyltransferase EC 2.1.1.234: dTDP-3-amino-3,4,6-trideoxy-α-D-glucopyranose N,N-dimethyltransferase EC 2.1.1.235: dTDP-3-amino-3,6-dideoxy-α-D-glucopyranose N,N-dimethyltransferase EC 2.1.1.236: dTDP-3-amino-3,6-dideoxy-α-D-galactopyranose N,N-dimethyltransferase EC 2.1.1.237: mycinamicin III 3′′-O-methyltransferase EC 2.1.1.238: mycinamicin VI 2′′-O-methyltransferaseD EC 2.1.1.239: L-olivosyl-oleandolide 3-O-methyltransferase EC 2.1.1.240: trans-resveratrol di-O-methyltransferase EC 2.1.1.241: 2,4,7-trihydroxy-1,4-benzoxazin-3-one-glucoside 7-O-methyltransferase EC 2.1.1.242: 16S rRNA (guanine1516-N2)-methyltransferase EC 2.1.1.243: 2-ketoarginine methyltransferase EC 2.1.1.244: protein N-terminal methyltransferase EC 2.1.1.245: 5-methyltetrahydrosarcinapterin—corrinoid/iron-sulfur protein Co-methyltransferase EC 2.1.1.246: [methyl-Co(III) methanol-specific corrinoid protein]—coenzyme M methyltransferase EC 2.1.1.247: (methyl-Co(III) methylamine-specific corrinoid protein)—coenzyme M methyltransferase EC 2.1.1.248: methylamine—corrinoid protein Co-methyltransferase EC 2.1.1.249: dimethylamine—corrinoid protein Co-methyltransferase EC 2.1.1.250: trimethylamine—corrinoid protein Co-methyltransferase EC 2.1.1.251: methylated-thiol—coenzyme M methyltransferase EC 2.1.1.252: tetramethylammonium—corrinoid protein Co-methyltransferase EC 2.1.1.253: [methyl-Co(III) tetramethylammonium-specific corrinoid protein]—coenzyme M methyltransferase EC 2.1.1.254: erythromycin 3′′-O-methyltransferase EC 2.1.1.255: geranyl diphosphate 2-C-methyltransferase EC 2.1.1.256: tRNA (guanine6-N6-methyltransferase) EC 2.1.1.257: tRNA (pseudouridine54-N1)-methyltransferase EC 2.1.1.258: 5-methyltetrahydrofolate—corrinoid/iron-sulfur protein Co-methyltransferase EC 2.1.1.259: [fructose-bisphosphate aldolase]-lysine N-methyltransferase EC 2.1.1.260: rRNA small subunit pseudouridine methyltransferase Nep1 EC 2.1.1.261: 4-dimethylallyltryptophan N-methyltransferase EC 2.1.1.262: squalene methyltransferase EC 2.1.1.263: botryococcene C-methyltransferase EC 2.1.1.264: 23S rRNA (guanine2069-N7)-methyltransferase EC 2.1.1.265: tellurite methyltransferase EC 2.1.1.266: 23S rRNA (adenine2030-N6)-methyltransferase EC 2.1.1.267: flavonoid 3′,5′-methyltransferase EC 2.1.1.268: tRNAThr (cytosine32-N3)-methyltransferase EC 2.1.1.269: dimethylsulfoniopropionate demethylase EC 2.1.1.270: (+)-6a-hydroxymaackiain 3-O-methyltransferase EC 2.1.1.271: cobalt-precorrin-4 methyltransferase EC 2.1.1.272: cobalt-factor III methyltransferase EC 2.1.1.273: benzoate O-methyltransferase EC 2.1.1.274: salicylate 1-O-methyltransferase EC 2.1.1.275: gibberellin A9 O-methyltransferase EC 2.1.1.276: gibberellin A4 carboxyl methyltransferase EC 2.1.1.277: anthranilate O-methyltransferase EC 2.1.1.278: indole-3-acetate O-methyltransferase EC 2.1.1.279: trans-anol O-methyltransferase EC 2.1.1.280: selenocysteine Se-methyltransferase EC 2.1.1.281: phenylpyruvate C3-methyltransferase EC 2.1.1.282: tRNAPhe 7-[(3-amino-3-carboxypropyl)-4-demethylwyosine37-N4]-methyltransferase EC 2.1.1.283: emodin O-methyltransferase EC 2.1.1.284: 8-demethylnovobiocic acid C8-methyltransferase EC 2.1.1.285: demethyldecarbamoylnovobiocin O-methyltransferase EC 2.1.1.286: 25S rRNA (adenine2142-N1)-methyltransferase EC 2.1.1.287: 25S rRNA (adenine645-N1)-methyltransferase EC 2.1.1.288: aklanonic acid methyltransferase EC 2.1.1.289: cobalt-precorrin-7 (C5)-methyltransferase EC 2.1.1.290: tRNAPhe [7-(3-amino-3-carboxypropyl)wyosine37-O]-methyltransferase EC 2.1.1.291: (R,S)-reticuline 7-O-methyltransferase EC 2.1.1.292: carminomycin 4-O-methyltransferase EC 2.1.1.293: 6-hydroxytryprostatin B O-methyltransferase EC 2.1.1.294: 3-O-phospho-polymannosyl GlcNAc-diphospho-ditrans,octacis-undecaprenol 3-phospho-methyltransferase EC 2.1.1.295: 2-methyl-6-phytyl-1,4-hydroquinone methyltransferase EC 2.1.1.296: methyltransferase cap2 EC 2.1.1.297: peptide chain release factor N5-glutamine methyltransferase EC 2.1.1.298: ribosomal protein L3 N5-glutamine methyltransferase EC 2.1.1.299: protein N-terminal monomethyltransferase EC 2.1.1.300: pavine N-methyltransferase EC 2.1.1.301: cypemycin N-terminal methyltransferase EC 2.1.1.302: 3-hydroxy-5-methyl-1-naphthoate 3-O-methyltransferase EC 2.1.1.303: 2,7-dihydroxy-5-methyl-1-naphthoate 7-O-methyltransferase EC 2.1.1.304: L-tyrosine C3-methyltransferase EC 2.1.1.305: 8-demethyl-8-α-L-rhamnosyltetracenomycin-C 2′-O-methyltransferase EC 2.1.1.306: 8-demethyl-8-(2-methoxy-α-L-rhamnosyl)tetracenomycin-C 3′-O-methyltransferase EC 2.1.1.307: 8-demethyl-8-(2,3-dimethoxy-α-L-rhamnosyl)tetracenomycin-C 4′-O-methyltransferase EC 2.1.1.308: cytidylyl-2-hydroxyethylphosphonate methyltransferase EC 2.1.1.309: 18S rRNA (guanine1575-N7)-methyltransferase EC 2.1.1.310: 25S rRNA (cytosine2870-C5)-methyltransferase EC 2.1.1.311: 25S rRNA (cytosine2278-C5)-methyltransferase EC 2.1.1.312: 25S rRNA (uracil2843-N3)-methyltransferase EC 2.1.1.313: 25S rRNA (uracil2634-N3)-methyltransferase EC 2.1.1.314: diphthine methyl ester synthase EC 2.1.1.315: 27-O-demethylrifamycin SV methyltransferase EC 2.1.1.316: mitomycin 6-O-methyltransferase EC 2.1.1.317: sphingolipid C9-methyltransferase EC 2.1.1.318: [trehalose-6-phosphate synthase]-L-cysteine S-methyltransferase EC 2.1.1.319: type I protein arginine methyltransferase EC 2.1.1.320: type II protein arginine methyltransferase EC 2.1.1.321: type III protein arginine methyltransferase EC 2.1.1.322: type IV protein arginine methyltransferase EC 2.1.1.323: (–)-pluviatolide 4-O-methyltransferase EC 2.1.1.324: dTDP-4-amino-2,3,4,6-tetradeoxy-D-glucose N,N-dimethyltransferase EC 2.1.1.325: juvenile hormone-III synthase EC 2.1.1.326: N-acetyldemethylphosphinothricin P-methyltransferase EC 2.1.1.327: phenazine-1-carboxylate N-methyltransferase EC 2.1.1.328: N-demethylindolmycin N-methyltransferase EC 2.1.1.329: demethylphylloquinol methyltransferase EC 2.1.1.330: 5′-demethylyatein 5′-O-methyltransferase EC 2.1.1.331: bacteriochlorophyllide d C-121-methyltransferase EC 2.1.1.332: bacteriochlorophyllide d C-82-methyltransferase EC 2.1.1.333: bacteriochlorophyllide d C-20 methyltransferase EC 2.1.1.334: methanethiol S-methyltransferase EC 2.1.1.335: 4-amino-anhydrotetracycline N4-methyltransferase EC 2.1.1.336: norbelladine O-methyltransferase EC 2.1.1.337: reticuline N-methyltransferase EC 2.1.1.338: desmethylxanthohumol 6′-O-methyltransferase EC 2.1.1.339: xanthohumol 4-O-methyltransferase EC 2.1.1.340: 3-aminomethylindole N'-methyltransferase EC 2.1.1.341: vanillate/3-O-methylgallate O-demethylase EC 2.1.1.342: anaerobilin synthase EC 2.1.1.343: 8-amino-8-demethylriboflavin N,N-dimethyltransferase EC 2.1.1.344: ornithine lipid N-methyltransferase EC 2.1.1.345: psilocybin synthase EC 2.1.1.346: U6 snRNA m6A methyltransferase EC 2.1.1.347: (+)-O-methylkolavelool synthase EC 2.1.1.348: mRNA m6A methyltransferase EC 2.1.1.349: toxoflavin synthase EC 2.1.1.350: menaquinone C8-methyltransferase EC 2.1.1.351: nocamycin O-methyltransferase EC 2.1.1.352: 3-O-acetyl-4′-O-demethylpapaveroxine 4′-O-methyltransferase EC 2.1.1.353: demethylluteothin O-methyltransferase EC 2.1.1.354: [histone H3]-lysine4 N-trimethyltransferase EC 2.1.1.355: [histone H3]-lysine9 N-trimethyltransferase EC 2.1.1.356: [histone H3]-lysine27 N-trimethyltransferase EC 2.1.1.357: [histone H3]-lysine36 N-dimethyltransferase EC 2.1.1.358: [histone H3]-dimethyl-L-lysine36 N-methyltransferase. Now known to have the activity of EC 2.1.1.359, [histone H3]-lysine36 N-trimethyltransferase. EC 2.1.1.359: [histone H3]-lysine36 N-trimethyltransferase EC 2.1.1.360: [histone H3]-lysine79 N-trimethyltransferase EC 2.1.1.361: [histone H4]-lysine20 N-methyltransferase EC 2.1.1.362: [histone H4]-N-methyl-L-lysine20 N-methyltransferase EC 2.1.1.363: pre-sodorifen synthase EC 2.1.1.364: [histone H3]-lysine4 N-methyltransferase EC 2.1.1.365: MMP 1-O-methyltransferase EC 2.1.1.366: [histone H3]-N6,N6-dimethyl-lysine9 N-methyltransferase EC 2.1.1.367: [histone H3]-lysine9 N-methyltransferase EC 2.1.1.368: [histone H3]-lysine9 N-dimethyltransferase EC 2.1.1.369: [histone H3]-lysine27 N-methyltransferase EC 2.1.1.370: [histone H3]-lysine4 N-dimethyltransferase EC 2.1.1.371: [histone H3]-lysine27 N-dimethyltransferase EC 2.1.1.372: [histone H4]-lysine20 N-trimethyltransferase EC 2.1.1.373: 2-hydroxy-4-(methylsulfanyl)butanoate S-methyltransferase EC 2.1.1.374: 2-heptyl-1-hydroxyquinolin-4(1H)-one methyltransferase EC 2.1.1.375: NNS virus cap methyltransferase EC 2.1.1.376: glycine betaine—corrinoid protein Co-methyltransferase EC 2.1.1.377: [methyl-Co(III) glycine betaine-specific corrinoid protein]—coenzyme M methyltransferase EC 2.1.1.378: [methyl-Co(III) glycine betaine-specific corrinoid protein]—tetrahydrofolate methyltransferase EC 2.1.1.379: [methyl coenzyme M reductase]-L-arginine C-5-methyltransferase
==== Cyanopyrrolidines ==== Cyanopyrrolidines have two key interactions to the DPP-4 complex: 1. Nitrile in the position of the scissile bond of the peptidic substrate that is important for high potency. The nitrile group forms reversible covalent bonds with the catalytically active serine hydroxyl (Ser630), i.e. cyanopyrrolidines are competitive inhibitors with slow dissociation kinetics. 2. Hydrogen bonding network between the protonated amino group and a negatively charged region of the protein surface, Glu205, Glu206 and Tyr662. All cyanopyrrolidines have basic, primary or secondary amine, which makes this network possible but these compounds usually drop in potency if these amines are changed. Nonetheless, two patent applications unveil that the amino group can be changed, i.e. replaced by a hydrazine, but it is claimed that these compounds do not only act via DPP-4 inhibition but also prevent diabetic vascular complications by acting as a radical scavenger.
Sources: en.wikipedia.org
=== Stimulation === The hypothalamus coordinates many hormonal and behavioural circadian rhythms, complex patterns of neuroendocrine outputs, complex homeostatic mechanisms, and important behaviours. The hypothalamus must, therefore, respond to many different signals, some of which are generated externally and some internally. Delta wave signalling arising either in the thalamus or in the cortex influences the secretion of releasing hormones; GHRH and prolactin are stimulated whilst TRH is inhibited. The hypothalamus is responsive to:
Anguilla - The Scout Association of Anguilla Bermuda - Bermuda Scout Association Cayman Islands - The Scout Association of the Cayman Islands Falkland Islands - Scouting and Guiding in the Falkland Islands Gibraltar - The Scout Association of Gibraltar Montserrat - The Scout Association of Montserrat Saint Helena and Ascension Island - Scouting and Guiding on Saint Helena and Ascension Island Turks and Caicos Islands - The Scout Association of the Turks and Caicos British Virgin Islands - The Scout Association of the British Virgin Islands United States
The GerN and GrmA proteins of Bacillus cereus and Bacillus megaterium, respectively, are spore germination proteins that can exchange Na+ for H+ and/or K+. The AmhT homologue of Bacillus pseudofirmus transports both K+ and NH4+, influences ammonium homeostasis, and is required for normal sporulation and germination. The identification of these proteins as members of the CPA2 family reveals that monovalent cation transport is required for Bacillus spore formation and germination.
== Legal status == As of March 2022, the European Commission has taken new measures to control the psychoactive substance of 3-CMC. This decision is based on a risk assessment conducted by the EU Drugs Agency (EMCDDA) in November 2021. Since 3-CMC was prohibited in China (October 2015), it was found that most of the production was manufactured in India and little of the substance supply originates from inside Europe. Several European countries were ahead of the European Commission report by (generically) controlling the substance. Nowadays, in almost all countries 3-CMC is prohibited.
Sources: en.wikipedia.org
Dry ice is produced industrially through the compression and cooling of carbon dioxide. The most common industrial method of manufacturing dry ice starts with a gas having a high concentration of carbon dioxide. Such gases can be a byproduct of another process, such as producing ammonia from nitrogen and natural gas, oil refinery activities or large-scale fermentation. The carbon dioxide-rich gas is then pressurized and refrigerated until it liquefies. Next, the pressure is reduced. When this occurs some liquid carbon dioxide vaporizes, causing a rapid lowering of temperature of the remaining liquid. As a result, the extreme cold causes the liquid to solidify into a snow-like consistency. Finally, the snow-like solid carbon dioxide is compressed into small pellets or larger blocks of dry ice. Dry ice is typically produced in three standard forms: large blocks, small (1⁄2 or 5⁄8 in [13 or 16 mm] diameter) cylindrical pellets and tiny (1⁄8 inch [3.2 mm] diameter) cylindrical, high surface to volume pellets that float on oil or water and do not stick to skin because of their high radii of curvature. Tiny dry ice pellets are used primarily for dry ice blasting, quick freezing, fire fighting, oil solidifying and have been found to be safe for experimentation by middle school students wearing appropriate personal protective equipment such as gloves and safety glasses. A standard block weighing approximately 30 kg (66 lb) covered in a taped paper wrapping is most common.
It propped up friendly puppet politicians and supported right-wing militias to maintain power. Workers often organized and went on strike against these conditions, forming local militias against the United Fruit Company. This would usually lead to conflict between the two sides, which culminated in a strike in November 1928 by farmers in Ciénaga for better working conditions. The striking workers called for an end to temporary contracts, the creation of mandatory worker insurance, the creation of compensation for work accidents, the creation of hygienic dormitories, a 6-day work week, the implementation of a minimum wage, the abolishment of wages through company coupons and office stores, and the recognition of farmers and tenants as employees with legal rights. The strike quickly grew, becoming the largest in Colombia's history, with many socialists, anarchists, Marxists, and leftists joining and organizing the strike. The United Fruit Company demanded that the workers and the union disband. Following several weeks of failed negotiations, the Colombian government of Miguel Abadía Méndez sent the Colombian Army to Ciénaga. After a standoff with the strikers, the Army shot into the crowd of strikers, killing between 68 and 2,000 people, in what became known as the Banana Massacre. This led to an outrage in the Colombian public, creating an explosion of leftist and revolutionary organizations. In Bogotá, leftist students protested and organized against the Colombian government, eventually hoping to overthrow it. This opposition exploded in 1948.
Sometimes the use of non-invasive methods is not an option, so that the next level of minimally invasive techniques are looked to. These include the use of hypodermic injection (using the syringe), an endoscope, percutaneous surgery which involves needle puncture of the skin, laparoscopic surgery commonly called keyhole surgery, a coronary catheter, angioplasty and stereotactic surgery.
==== Diabetes ==== The high doses of nicotinic acid used to treat hyperlipidemia have been shown to elevate fasting blood glucose in people with type 2 diabetes. Long-term nicotinic acid therapy was also associated with an increase in the risk of new-onset type 2 diabetes.
The hydrophobic effect can be quantified by measuring the partition coefficients of non-polar molecules between water and non-polar solvents. The partition coefficients can be transformed to free energy of transfer which includes enthalpic and entropic components, ΔG = ΔH - TΔS. These components are experimentally determined by calorimetry. The hydrophobic effect was found to be entropy-driven at room temperature because of the reduced mobility of water molecules in the solvation shell of the non-polar solute; however, the enthalpic component of transfer energy was found to be favorable, meaning it strengthened water-water hydrogen bonds in the solvation shell due to the reduced mobility of water molecules. At the higher temperature, when water molecules become more mobile, this energy gain decreases along with the entropic component. The hydrophobic effect depends on the temperature, which leads to "cold denaturation" of proteins. The hydrophobic effect can be calculated by comparing the free energy of solvation with bulk water. In this way, the hydrophobic effect not only can be localized but also decomposed into enthalpic and entropic contributions.
Sources: en.wikipedia.org
Collapse occurs when the product temperature rises above its collapse or eutectic temperature during drying. The frozen matrix loses structure, producing a shrunken or melted appearance. This can slow reconstitution and may affect stability.
Karl Fischer titration is a common method, along with loss on drying and thermogravimetric analysis. Each method has different sensitivity and sample requirements. Results should be interpreted with the product's formulation and container in mind.
No. Lyophilization removes water but is not a sterilization step. Sterile products are typically filtered and filled aseptically before freezing, and container closure integrity is maintained afterward.
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.