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�»“构特征与受体作用机制 — Beginner to Advanced

By Editorial Desk · published 2025-09-06 · last reviewed 2025-10-15 · Data

Everything below concerns GLP-1 receptor agonist. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.

Last reviewed on 2025-10-15. Where a claim depends on a specific study, the study is described rather than over-claimed.

结构特征与受体作用机制

皮下注射后吸收相对缓慢,绝对生物利用度约为百分之八十九,血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢,终末半衰期约为一百六十五小时,接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升,血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主,相关产物主要经尿液与粪便排出。

序列层面的改动同时解决了两个问题,即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟,主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库,使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发,属于该类药物化学改造的典型范式。

Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物,其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代,使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸,进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链,该侧链赋予分子与血浆白蛋白结合的能力。

Background and Molecular Profile

Two principal therapeutic variants exist under separate regulatory filings, one indicated for glycemic control in type 2 diabetes and one for chronic weight management. Both use the same active molecule; differences lie in formulation strength, titration schedule, and labeling. Regulatory agencies in the United States and European Union approved injectable forms in 2017 and 2018 respectively. An oral tablet formulation received approval later, using a carrier molecule to enhance absorption across the gastric epithelium. Labeling differs by jurisdiction and by indication.

The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.

Semaglutide at a glance

PropertyValueNotes
分子式C187H291N45O59按主链与 C18 二酸侧链计算
分子量约 4113.6 道尔顿游离碱形式,随反离子略有差异
外观白色至类白色冻干粉末具吸湿性,需干燥保存
溶解性微溶于水,易溶于碱性缓冲液溶解性随 pH 升高而改善
等电点约 5.4影响缓冲液选择与聚集倾向

Background and Mechanism of Action

Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.

Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.

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Handling, Storage, and Characterization

Semaglutide dissolves readily in water and in aqueous buffers near neutral pH. Solubility decreases near the isoelectric point, where net charge is minimal. Common laboratory solvents include phosphate-buffered saline and dilute ammonium bicarbonate. Strongly acidic or basic conditions may accelerate hydrolysis. Working concentrations are usually prepared by diluting a concentrated stock. Vial surfaces can adsorb small amounts of peptide at low concentrations, so carrier proteins or low-binding tubes are sometimes used.

Reverse-phase high-performance liquid chromatography is the standard method for purity assessment, separating the peptide from truncated or oxidized variants. Mass spectrometry confirms molecular mass and detects modifications, while ultraviolet absorbance near 280 nanometers supports concentration measurement through tryptophan and tyrosine residues. Circular dichroism can indicate secondary structure, though the peptide is largely helical in solution, and ion-exchange chromatography resolves charge variants. Purity values above 95 percent are typical for research-grade material. Stability studies track degradation over time under defined conditions.

Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.

Peptide Background and Receptor Mechanism

Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.

Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.

Mechanism and Pharmacological Class

Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.

Semaglutide belongs to the glucagon-like peptide-1 receptor agonist class, a group of synthetic peptides that imitate an incretin hormone released by intestinal L cells after food intake. Native GLP-1 circulates for only a few minutes because dipeptidyl peptidase-4 cleaves it rapidly. The hormone acts on pancreatic islets, the gastrointestinal tract, and several brain regions. Because the natural peptide is short-lived, development work concentrated on analogues that keep receptor activity while resisting enzymatic breakdown and renal clearance.

Reference notes

=== Intragenic complementation === When multiple copies of a polypeptide encoded by a gene form a complex, this protein structure is referred to as a multimer. When a multimer is formed from polypeptides produced by two different mutant alleles of a particular gene, the mixed multimer may exhibit greater functional activity than the unmixed multimers formed by each of the mutants alone. In such a case, the phenomenon is referred to as intragenic complementation (also called inter-allelic complementation). Intragenic complementation has been demonstrated in many different genes in a variety of organisms including the fungi Neurospora crassa, Saccharomyces cerevisiae and Schizosaccharomyces pombe; the bacterium Salmonella typhimurium; the virus bacteriophage T4, an RNA virus and humans. In such studies, numerous mutations defective in the same gene were often isolated and mapped in a linear order on the basis of recombination frequencies to form a genetic map of the gene. Separately, the mutants were tested in pairwise combinations to measure complementation. An analysis of the results from such studies led to the conclusion that intragenic complementation, in general, arises from the interaction of differently defective polypeptide monomers to form a multimer. Genes that encode multimer-forming polypeptides appear to be common.

Gold nanoparticles show potential as intracellular delivery vehicles for antisense oligonucleotides (single and double stranded DNA) by providing protection against intracellular nucleases and ease of functionalization for selective targeting.

Now EC 1.1.1.303, diacetyl reductase [(R)-acetoin forming] and EC 1.1.1.304, diacetyl reductase [(S)-acetoin forming] EC 1.1.1.6: glycerol dehydrogenase EC 1.1.1.7: propanediol-phosphate dehydrogenase EC 1.1.1.8: glycerol-3-phosphate dehydrogenase (NAD+) EC 1.1.1.9: D-xylulose reductase EC 1.1.1.10: L-xylulose reductase EC 1.1.1.11: D-arabinitol 4-dehydrogenase EC 1.1.1.12: L-arabinitol 4-dehydrogenase EC 1.1.1.13: L-arabinitol 2-dehydrogenase EC 1.1.1.14: L-iditol 2-dehydrogenase EC 1.1.1.15: D-iditol 2-dehydrogenase EC 1.1.1.16: galactitol 2-dehydrogenase EC 1.1.1.17: mannitol-1-phosphate 5-dehydrogenase EC 1.1.1.18: inositol 2-dehydrogenase EC 1.1.1.19: glucuronate reductase EC 1.1.1.20: glucuronolactone reductase EC 1.1.1.207: (-)-menthol dehydrogenase EC 1.1.1.208: (+)-neomenthol dehydrogenase EC 1.1.1.21: aldose reductase EC 1.1.1.22: UDP-glucose 6-dehydrogenase EC 1.1.1.222: (R)-4-hydroxyphenyllactate dehydrogenase EC 1.1.1.23: histidinol dehydrogenase| EC 1.1.1.24: quinate/shikimate dehydrogenase (NAD+) EC 1.1.1.25: shikimate dehydrogenase (NADP+) EC 1.1.1.26: glyoxylate reductase EC 1.1.1.27: L-lactate dehydrogenase EC 1.1.1.28: D-lactate dehydrogenase EC 1.1.1.29: glycerate dehydrogenase EC 1.1.1.30: 3-hydroxybutyrate dehydrogenase EC 1.1.1.31: 3-hydroxyisobutyrate dehydrogenase EC 1.1.1.32: mevaldate reductase EC 1.1.1.33: mevaldate reductase (NADPH) EC 1.1.1.34: hydroxymethylglutaryl-CoA reductase (NADPH) EC 1.1.1.35: 3-hydroxyacyl-CoA dehydrogenase EC 1.1.1.36: acetoacetyl-CoA reductase EC 1.1.1.37: malate dehydrogenase EC 1.1.1.38: malate dehydrogenase (oxaloacetate-decarboxylating) EC 1.1.1.39: malate dehydrogenase (decarboxylating) EC 1.1.1.40: malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) EC 1.1.1.41: isocitrate dehydrogenase (NAD+) EC 1.1.1.42: isocitrate dehydrogenase (NADP+) EC 1.1.1.43: phosphogluconate 2-dehydrogenase EC 1.1.1.44: phosphogluconate dehydrogenase (NADP+-dependent, decarboxylating) EC 1.1.1.45: L-gulonate 3-dehydrogenase EC 1.1.1.46: L-arabinose 1-dehydrogenase EC 1.1.1.47: glucose 1-dehydrogenase [NAD(P)+)] EC 1.1.1.48: D-galactose 1-dehydrogenase EC 1.1.1.49: glucose-6-phosphate dehydrogenase (NADP+) EC 1.1.1.50: 3α-hydroxysteroid 3-dehydrogenase (Si-specific) EC 1.1.1.51: 3(or 17)β-hydroxysteroid dehydrogenase EC 1.1.1.52: 3α-hydroxycholanate dehydrogenase (NAD+) EC 1.1.1.53: 3α(or 20β)-hydroxysteroid dehydrogenase EC 1.1.1.54: allyl-alcohol dehydrogenase EC 1.1.1.55: lactaldehyde reductase (NADPH) EC 1.1.1.56: ribitol 2-dehydrogenase EC 1.1.1.57: fructuronate reductase EC 1.1.1.58: tagaturonate reductase EC 1.1.1.59: 3-hydroxypropionate dehydrogenase EC 1.1.1.60: 2-hydroxy-3-oxopropionate reductase EC 1.1.1.61: 4-hydroxybutyrate dehydrogenase EC 1.1.1.62: 17β-estradiol 17-dehydrogenase EC 1.1.1.63: testosterone 17β-dehydrogenase. Now EC 1.1.1.239, 3α(17β)-hydroxysteroid dehydrogenase (NAD+) EC 1.1.1.64: testosterone 17β-dehydrogenase (NADP+) EC 1.1.1.65: pyridoxine 4-dehydrogenase EC 1.1.1.66: ω-hydroxydecanoate dehydrogenase EC 1.1.1.67: mannitol 2-dehydrogenase EC 1.1.1.68: 5,10-methylenetetrahydrofolate reductase. Now EC 1.5.1.20, methylenetetrahydrofolate reductase [NAD(P)H] EC 1.1.1.69: gluconate 5-dehydrogenase EC 1.1.1.70: D-glucuronolactone dehydrogenase. Now included with EC 1.2.1.3 aldehyde dehydrogenase (NAD+) EC 1.1.1.71: alcohol dehydrogenase [NAD(P)+] EC 1.1.1.72: glycerol dehydrogenase (NADP+) EC 1.1.1.73: octanol dehydrogenase EC 1.1.1.74: D-aminopropanol dehydrogenase (reaction due to EC 1.1.1.4 (R,R)-butanediol dehydrogenase) EC 1.1.1.75: (R)-aminopropanol dehydrogenase EC 1.1.1.76: (S,S)-butanediol dehydrogenase EC 1.1.1.77: lactaldehyde reductase EC 1.1.1.78: methylglyoxal reductase (NADH-dependent) EC 1.1.1.79: glyoxylate reductase (NADP+) EC 1.1.1.80: isopropanol dehydrogenase (NADP+) EC 1.1.1.81: hydroxypyruvate reductase EC 1.1.1.82: malate dehydrogenase (NADP+) EC 1.1.1.83: D-malate dehydrogenase (decarboxylating) EC 1.1.1.84: dimethylmalate dehydrogenase EC 1.1.1.85: 3-isopropylmalate dehydrogenase EC 1.1.1.86: ketol-acid reductoisomerase (NADP+) EC 1.1.1.87: homoisocitrate dehydrogenase EC 1.1.1.88: hydroxymethylglutaryl-CoA reductase EC 1.1.1.89: dihydroxyisovalerate dehydrogenase (isomerizing). Now included with EC 1.1.1.86 ketol-acid reductoisomerase EC 1.1.1.90: aryl-alcohol dehydrogenase EC 1.1.1.91: aryl-alcohol dehydrogenase (NADP+) EC 1.1.1.92: oxaloglycolate reductase (decarboxylating) EC 1.1.1.93: tartrate dehydrogenase EC 1.1.1.94: glycerol-3-phosphate dehydrogenase [NAD(P)+] EC 1.1.1.95: phosphoglycerate dehydrogenase EC 1.1.1.96: diiodophenylpyruvate reductase EC 1.1.1.97: 3-hydroxybenzyl-alcohol dehydrogenase EC 1.1.1.98: (R)-2-hydroxy-fatty-acid dehydrogenase EC 1.1.1.99: (S)-2-hydroxy-fatty-acid dehydrogenase EC 1.1.1.100: 3-oxoacyl-[acyl-carrier-protein] reductase EC 1.1.1.101: acylglycerone-phosphate reductase EC 1.1.1.102: 3-dehydrosphinganine reductase EC 1.1.1.103: L-threonine 3-dehydrogenase EC 1.1.1.104: 4-oxoproline reductase EC 1.1.1.105: all-trans-retinol dehydrogenase (NAD+) EC 1.1.1.106: pantoate 4-dehydrogenase EC 1.1.1.107: pyridoxal 4-dehydrogenase EC 1.1.1.108: carnitine 3-dehydrogenase EC 1.1.1.109: Now EC 1.3.1.28, 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase EC 1.1.1.110: aromatic 2-oxoacid reductase EC 1.1.1.111: 3-(imidazol-5-yl)lactate dehydrogenase EC 1.1.1.112: indanol dehydrogenase EC 1.1.1.113: L-xylose 1-dehydrogenase EC 1.1.1.114: apiose 1-reductase EC 1.1.1.115: ribose 1-dehydrogenase (NADP+) EC 1.1.1.116: D-arabinose 1-dehydrogenase (NAD+) EC 1.1.1.117: D-arabinose 1-dehydrogenase [NAD(P)+] EC 1.1.1.118: glucose 1-dehydrogenase (NAD+) EC 1.1.1.119: glucose 1-dehydrogenase (NADP+) EC 1.1.1.120: galactose 1-dehydrogenase (NADP+) EC 1.1.1.121: aldose 1-dehydrogenase (NAD+) EC 1.1.1.122: D-threo-aldose 1-dehydrogenase EC 1.1.1.123: sorbose 5-dehydrogenase (NADP+) EC 1.1.1.124: fructose 5-dehydrogenase (NADP+) EC 1.1.1.125: 2-deoxy-D-gluconate 3-dehydrogenase EC 1.1.1.126: 2-dehydro-3-deoxy-D-gluconate 6-dehydrogenase EC 1.1.1.127: 2-dehydro-3-deoxy-D-gluconate 5-dehydrogenase EC 1.1.1.128: The reaction described is covered by EC 1.1.1.264, L-idonate 5-dehydrogenase. EC 1.1.1.129: L-threonate 3-dehydrogenase EC 1.1.1.130: 3-dehydro-L-gulonate 2-dehydrogenase EC 1.1.1.131: mannuronate reductase EC 1.1.1.132: GDP-mannose 6-dehydrogenase EC 1.1.1.133: dTDP-4-dehydrorhamnose reductase EC 1.1.1.134: dTDP-6-deoxy-L-talose 4-dehydrogenase (NADP+) EC 1.1.1.135: GDP-6-deoxy-D-talose 4-dehydrogenase EC 1.1.1.136: UDP-N-acetylglucosamine 6-dehydrogenase EC 1.1.1.137: ribitol-5-phosphate 2-dehydrogenase EC 1.1.1.138: mannitol 2-dehydrogenase (NADP+) EC 1.1.1.139: polyol dehydrogenase (NADP+). Now included with EC 1.1.1.21 aldehyde reductase EC 1.1.1.140: sorbitol-6-phosphate 2-dehydrogenase EC 1.1.1.141: 15-hydroxyprostaglandin dehydrogenase (NAD+) EC 1.1.1.142: D-pinitol dehydrogenase EC 1.1.1.143: sequoyitol dehydrogenase EC 1.1.1.144: perillyl-alcohol dehydrogenase EC 1.1.1.145: 3β-hydroxy-Δ5-steroid dehydrogenase EC 1.1.1.146: 11β-hydroxysteroid dehydrogenase EC 1.1.1.147: 16α-hydroxysteroid dehydrogenase EC 1.1.1.148: estradiol 17α-dehydrogenase EC 1.1.1.149: 20α-hydroxysteroid dehydrogenase EC 1.1.1.150: 21-hydroxysteroid dehydrogenase (NAD+) EC 1.1.1.151: 21-hydroxysteroid dehydrogenase (NADP+) EC 1.1.1.152: 3α-hydroxy-5β-androstane-17-one 3α-dehydrogenase EC 1.1.1.153: sepiapterin reductase (L-erythro-7,8-dihydrobiopterin forming) EC 1.1.1.154: ureidoglycolate dehydrogenase EC 1.1.1.155: homoisocitrate dehydrogenase. The enzyme is identical to EC 1.1.1.87, homoisocitrate dehydrogenase EC 1.1.1.156: glycerol 2-dehydrogenase (NADP+) EC 1.1.1.157: 3-hydroxybutyryl-CoA dehydrogenase EC 1.1.1.158: Now EC 1.3.1.98, UDP-N-acetylmuramate dehydrogenase EC 1.1.1.159: 7α-hydroxysteroid dehydrogenase EC 1.1.1.160: dihydrobunolol dehydrogenase EC 1.1.1.161: The activity is part of EC 1.14.13.15, cholestanetriol 26-monooxygenase EC 1.1.1.162: erythrulose reductase EC 1.1.1.163: cyclopentanol dehydrogenase EC 1.1.1.164: hexadecanol dehydrogenase EC 1.1.1.165: 2-alkyn-1-ol dehydrogenase EC 1.1.1.166: hydroxycyclohexanecarboxylate dehydrogenase EC 1.1.1.167: hydroxymalonate dehydrogenase EC 1.1.1.168: 2-dehydropantolactone reductase (Re-specific) EC 1.1.1.169: 2-dehydropantoate 2-reductase EC 1.1.1.170: 3β-hydroxysteroid-4α-carboxylate 3-dehydrogenase (decarboxylating) EC 1.1.1.171: Now EC 1.5.1.20, methylenetetrahydrofolate reductase [NAD(P)H] EC 1.1.1.172: 2-oxoadipate reductase EC 1.1.1.173: L-rhamnose 1-dehydrogenase EC 1.1.1.174: cyclohexane-1,2-diol dehydrogenase EC 1.1.1.175: D-xylose 1-dehydrogenase EC 1.1.1.176: 12α-hydroxysteroid dehydrogenase EC 1.1.1.177: glycerol-3-phosphate 1-dehydrogenase (NADP+) EC 1.1.1.178: 3-hydroxy-2-methylbutyryl-CoA dehydrogenase EC 1.1.1.179: D-xylose 1-dehydrogenase (NADP+, D-xylono-1,5-lactone-forming) EC 1.1.1.180: Now included with EC 1.1.1.131 mannuronate reductase EC 1.1.1.181: cholest-5-ene-3β,7α-diol 3β-dehydrogenase EC 1.1.1.182: Now included with EC 1.1.1.198 (+)-borneol dehydrogenase, EC 1.1.1.227 (-)-borneol dehydrogenase and EC 1.1.1.228 (+)-sabinol dehydrogenase EC 1.1.1.183: geraniol dehydrogenase (NADP+) EC 1.1.1.184: carbonyl reductase (NADPH) EC 1.1.1.185: L-glycol dehydrogenase EC 1.1.1.186: dTDP-galactose 6-dehydrogenase EC 1.1.1.187: GDP-4-dehydro-D-rhamnose reductase EC 1.1.1.188: prostaglandin-F synthase EC 1.1.1.189: prostaglandin-E2 9-reductase EC 1.1.1.190: indole-3-acetaldehyde reductase (NADH) EC 1.1.1.191: indole-3-acetaldehyde reductase (NADPH) EC 1.1.1.192: long-chain-alcohol dehydrogenase EC 1.1.1.193: 5-amino-6-(5-phosphoribosylamino)uracil reductase EC 1.1.1.194: coniferyl-alcohol dehydrogenase EC 1.1.1.195: cinnamyl-alcohol dehydrogenase EC 1.1.1.196: 15-hydroxyprostaglandin-D dehydrogenase (NADP+) EC 1.1.1.197: 15-hydroxyprostaglandin dehydrogenase (NADP+) EC 1.1.1.198: (+)-borneol dehydrogenase EC 1.1.1.199: (S)-usnate reductase EC 1.1.1.200: aldose-6-phosphate reductase (NADPH) EC 1.1.1.228: (+)-sabinol dehydrogenase EC 1.1.1.251: galactitol-1-phosphate 5-dehydrogenase EC 1.1.1.252: tetrahydroxynaphthalene reductase EC 1.1.1.253: Now EC 1.5.1.33, pteridine reductase EC 1.1.1.254: (S)-carnitine 3-dehydrogenase EC 1.1.1.255: mannitol dehydrogenase EC 1.1.1.256: fluoren-9-ol dehydrogenase EC 1.1.1.257: 4-(hydroxymethyl)benzenesulfonate dehydrogenase EC 1.1.1.258: 6-hydroxyhexanoate dehydrogenase EC 1.1.1.259: 3-hydroxypimeloyl-CoA dehydrogenase EC 1.1.1.260: sulcatone reductase EC 1.1.1.261: sn-glycerol-1-phosphate dehydrogenase EC 1.1.1.262: 4-hydroxythreonine-4-phosphate dehydrogenase EC 1.1.1.263: 1,5-anhydro-D-fructose reductase EC 1.1.1.264: L-idonate 5-dehydrogenase EC 1.1.1.265: 3-methylbutanal reductase EC 1.1.1.266: dTDP-4-dehydro-6-deoxyglucose reductase EC 1.1.1.267: 1-deoxy-D-xylulose-5-phosphate reductoisomerase EC 1.1.1.268: 2-(R)-hydroxypropyl-CoM dehydrogenase EC 1.1.1.269: 2-(S)-hydroxypropyl-CoM dehydrogenase EC 1.1.1.270: 3β-hydroxysteroid 3-dehydrogenase EC 1.1.1.271: GDP-L-fucose synthase EC 1.1.1.272: D-2-hydroxyacid dehydrogenase (NADP+) EC 1.1.1.273: vellosimine dehydrogenase EC 1.1.1.274: 2,5-didehydrogluconate reductase (2-dehydro-D-gluconate-forming) EC 1.1.1.275: (+)-trans-carveol dehydrogenase EC 1.1.1.276: serine 3-dehydrogenase (NADP+) EC 1.1.1.277: 3β-hydroxy-5β-steroid dehydrogenase EC 1.1.1.278: 3β-hydroxy-5α-steroid dehydrogenase EC 1.1.1.279: (R)-3-hydroxyacid-ester dehydrogenase EC 1.1.1.280: (S)-3-hydroxyacid-ester dehydrogenase EC 1.1.1.281: GDP-4-dehydro-6-deoxy-D-mannose reductase EC 1.1.1.282: Quinate/shikimate dehydrogenase EC 1.1.1.283: methylglyoxal reductase (NADPH-dependent) EC 1.1.1.284: S-(hydroxymethyl)glutathione dehydrogenase EC 1.1.1.285: 3′′-deamino-3′′-oxonicotianamine reductase EC 1.1.1.286: isocitrate—homoisocitrate dehydrogenase EC 1.1.1.287: D-arabinitol dehydrogenase (NADP+) EC 1.1.1.288: xanthoxin dehydrogenase EC 1.1.1.289: sorbose reductase EC 1.1.1.290: 4-phosphoerythronate dehydrogenase EC 1.1.1.291: 2-hydroxymethylglutarate dehydrogenase EC 1.1.1.292: 1,5-anhydro-D-fructose reductase (1,5-anhydro-D-mannitol-forming) EC 1.1.1.293: tropinone reductase I. This enzyme was already in the Enzyme List as EC 1.1.1.206, tropine dehydrogenase so EC 1.1.1.293 has been withdrawn at the public-review stage EC 1.1.1.294: chlorophyll(ide) b reductase EC 1.1.1.295: momilactone-A synthase EC 1.1.1.296: dihydrocarveol dehydrogenase EC 1.1.1.297: limonene-1,2-diol dehydrogenase EC 1.1.1.298: 3-hydroxypropionate dehydrogenase (NADP+) EC 1.1.1.299: malate dehydrogenase [NAD(P)+)] EC 1.1.1.300: NADP-retinol dehydrogenase EC 1.1.1.301: D-arabitol-phosphate dehydrogenase EC 1.1.1.302: 2,5-diamino-6-(ribosylamino)-4(3H)-pyrimidinone 5′-phosphate reductase EC 1.1.1.303: Diacetyl reductase ((R)-acetoin forming) EC 1.1.1.304: Diacetyl reductase ((S)-acetoin forming) EC 1.1.1.305: UDP-glucuronic acid dehydrogenase (UDP-4-keto-hexauronic acid decarboxylating) EC 1.1.1.306: S-(hydroxymethyl)mycothiol dehydrogenase EC 1.1.1.307: D-xylose reductase EC 1.1.1.308: sulfopropanediol 3-dehydrogenase EC 1.1.1.309: phosphonoacetaldehyde reductase (NADH) EC 1.1.1.310: (S)-sulfolactate dehydrogenase EC 1.1.1.311: (S)-1-phenylethanol dehydrogenase EC 1.1.1.312: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal dehydrogenase EC 1.1.1.313: sulfoacetaldehyde reductase EC 1.1.1.314: Now known to be catalyzed by EC 1.14.14.95, germacrene A hydroxylase EC 1.1.1.315: 11-cis-retinol dehydrogenase EC 1.1.1.316: L-galactose 1-dehydrogenase EC 1.1.1.317: perakine reductase EC 1.1.1.318: eugenol synthase EC 1.1.1.319: isoeugenol synthase EC 1.1.1.320: benzil reductase [(S)-benzoin forming] EC 1.1.1.321: benzil reductase [(R)-benzoin forming] EC 1.1.1.322: (–)-endo-fenchol dehydrogenase EC 1.1.1.323: (+)-thujan-3-ol dehydrogenase EC 1.1.1.324: 8-hydroxygeraniol dehydrogenase EC 1.1.1.325: sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming) EC 1.1.1.326: zerumbone synthase EC 1.1.1.327: 5-exo-hydroxycamphor dehydrogenase EC 1.1.1.328: nicotine blue oxidoreductase EC 1.1.1.329: 2-deoxy-scyllo-inosamine dehydrogenase EC 1.1.1.330: very-long-chain 3-oxoacyl-CoA reductase EC 1.1.1.331: secoisolariciresinol dehydrogenase EC 1.1.1.332: chanoclavine-I dehydrogenase EC 1.1.1.333: decaprenylphospho-β-D-erythro-pentofuranosid-2-ulose 2-reductase EC 1.1.1.334: methylecgonone reductase EC 1.1.1.335: UDP-N-acetyl-2-amino-2-deoxyglucuronate dehydrogenase EC 1.1.1.336: UDP-N-acetyl-D-mannosamine dehydrogenase EC 1.1.1.337: L-2-hydroxycarboxylate dehydrogenase (NAD+) EC 1.1.1.338: (2R)-3-sulfolactate dehydrogenase (NADP+) EC 1.1.1.339: dTDP-6-deoxy-L-talose 4-dehydrogenase (NAD+) EC 1.1.1.340: 1-deoxy-11β-hydroxypentalenate dehydrogenase EC 1.1.1.341: CDP-abequose synthase EC 1.1.1.342: CDP-paratose synthase EC 1.1.1.343: phosphogluconate dehydrogenase (NAD+-dependent, decarboxylating) EC 1.1.1.344: dTDP-6-deoxy-L-talose 4-dehydrogenase [NAD(P)+] EC 1.1.1.345: D-2-hydroxyacid dehydrogenase (NAD+) EC 1.1.1.346: 2,5-didehydrogluconate reductase (2-dehydro-L-gulonate-forming) EC 1.1.1.347: geraniol dehydrogenase (NAD+) EC 1.1.1.348: (3R)-2′-hydroxyisoflavanone reductase EC 1.1.1.349: norsolorinic acid ketoreductase EC 1.1.1.350: ureidoglycolate dehydrogenase (NAD+) EC 1.1.1.351: phosphogluconate dehydrogenase [NAD(P)+-dependent, decarboxylating] EC 1.1.1.352: 5′-hydroxyaverantin dehydrogenase EC 1.1.1.353: versiconal hemiacetal acetate reductase EC 1.1.1.354: farnesol dehydrogenase (NAD+) EC 1.1.1.355: 2′-dehydrokanamycin reductase EC 1.1.1.356: GDP-L-colitose synthase EC 1.1.1.357: 3α-hydroxysteroid 3-dehydrogenase EC 1.1.1.358: 2-dehydropantolactone reductase EC 1.1.1.359: aldose 1-dehydrogenase [NAD(P)+] EC 1.1.1.360: glucose/galactose 1-dehydrogenase EC 1.1.1.361: glucose-6-phosphate 3-dehydrogenase EC 1.1.1.362: aklaviketone reductase EC 1.1.1.363: glucose-6-phosphate dehydrogenase [NAD(P)+] EC 1.1.1.364: dTDP-4-dehydro-6-deoxy-α-D-gulose 4-ketoreductase EC 1.1.1.365: D-galacturonate reductase EC 1.1.1.366: L-idonate 5-dehydrogenase (NAD+) EC 1.1.1.367: UDP-2-acetamido-2,6-β-L-arabino-hexul-4-ose reductase EC 1.1.1.368: 6-hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase EC 1.1.1.369: D-chiro-inositol 1-dehydrogenase EC 1.1.1.370: scyllo-inositol 2-dehydrogenase (NAD+) EC 1.1.1.371: scyllo-inositol 2-dehydrogenase (NADP+) EC 1.1.1.372: D/L-glyceraldehyde reductase EC 1.1.1.373: sulfolactaldehyde 3-reductase EC 1.1.1.374: UDP-N-acetylglucosamine 3-dehydrogenase EC 1.1.1.375: L-2-hydroxycarboxylate dehydrogenase [NAD(P)+] EC 1.1.1.376: L-arabinose 1-dehydrogenase [NAD(P)+] EC 1.1.1.377: L-rhamnose 1-dehydrogenase (NADP+) EC 1.1.1.378: L-rhamnose 1-dehydrogenase [NAD(P)+] EC 1.1.1.379: (R)-mandelate dehydrogenase EC 1.1.1.380: L-gulonate 5-dehydrogenase EC 1.1.1.381: 3-hydroxy acid dehydrogenase EC 1.1.1.382: ketol-acid reductoisomerase (NAD+) EC 1.1.1.383: ketol-acid reductoisomerase [NAD(P)+] EC 1.1.1.384: dTDP-3,4-didehydro-2,6-dideoxy-α-D-glucose 3-reductase EC 1.1.1.385: dihydroanticapsin dehydrogenase EC 1.1.1.386: ipsdienol dehydrogenase EC 1.1.1.387: L-serine 3-dehydrogenase (NAD+) EC 1.1.1.388: glucose-6-phosphate dehydrogenase (NAD+) EC 1.1.1.389: 2-dehydro-3-deoxy-L-galactonate 5-dehydrogenase EC 1.1.1.390: sulfoquinovose 1-dehydrogenase EC 1.1.1.391: 3β-hydroxycholanate 3-dehydrogenase (NAD+) EC 1.1.1.392: 3α-hydroxycholanate dehydrogenase (NADP+) EC 1.1.1.393: 3β-hydroxycholanate 3-dehydrogenase (NADP+) EC 1.1.1.394: aurachin B dehydrogenase EC 1.1.1.395: 3α-hydroxy bile acid-CoA-ester 3-dehydrogenase EC 1.1.1.396: bacteriochlorophyllide a dehydrogenase EC 1.1.1.397: β-methylindole-3-pyruvate reductase EC 1.1.1.398: 2-glutathionyl-2-methylbut-3-en-1-ol dehydrogenase EC 1.1.1.399: 2-oxoglutarate reductase EC 1.1.1.400: 2-methyl-1,2-propanediol dehydrogenase EC 1.1.1.401: 2-dehydro-3-deoxy-L-rhamnonate dehydrogenase (NAD+) EC 1.1.1.402: D-erythritol 1-phosphate dehydrogenase EC 1.1.1.403: D-threitol dehydrogenase (NAD+) EC 1.1.1.404: tetrachlorobenzoquinone reductase EC 1.1.1.405: ribitol-5-phosphate 2-dehydrogenase (NADP+) EC 1.1.1.406: galactitol 2-dehydrogenase (L-tagatose-forming) EC 1.1.1.407: D-altritol 5-dehydrogenase EC 1.1.1.408: 4-phospho-D-threonate 3-dehydrogenase EC 1.1.1.409: 4-phospho-D-erythronate 3-dehydrogenase EC 1.1.1.410: D-erythronate 2-dehydrogenase EC 1.1.1.411: L-threonate 2-dehydrogenase EC 1.1.1.412: 2-alkyl-3-oxoalkanoate reductase EC 1.1.1.413: A-factor type γ-butyrolactone 1′-reductase (1S-forming) EC 1.1.1.414: L-galactonate 5-dehydrogenase EC 1.1.1.415: noscapine synthase EC 1.1.1.416: isopyridoxal dehydrogenase (5-pyridoxolactone-forming) EC 1.1.1.417: 3β-hydroxysteroid-4β-carboxylate 3-dehydrogenase (decarboxylating) EC 1.1.1.418: plant 3β-hydroxysteroid-4α-carboxylate 3-dehydrogenase (decarboxylating) EC 1.1.1.419: nepetalactol dehydrogenase EC 1.1.1.420: D-apiose dehydrogenase EC 1.1.1.421: D-apionate oxidoisomerase EC 1.1.1.422: pseudoephedrine dehydrogenase EC 1.1.1.423: (1R,2S)-ephedrine 1-dehydrogenase EC 1.1.1.424: D-xylose 1-dehydrogenase (NADP+, D-xylono-1,4-lactone-forming) EC 1.1.1.425: levoglucosan dehydrogenase EC 1.1.1.426: UDP-N-acetyl-α-D-quinovosamine dehydrogenase

This effectiveness has been explained in a Realist Evaluation which explained the effectiveness through bystander effect, social identity theory, and skills training such that universal access to training supports social identity and in-group norms (of people who use drugs), which supports the conditions for the success of a peer-to-peer distribution model of naloxone-based interventions. Stigma and stigmatising attitudes reduced the effectiveness of naloxone based interventions.

Like many other anemones, S. helianthus can serve as a “hub” for mutualistic networks of species and has been documented to live in symbiosis with other organisms. Symbiosis refers to the close association between organisms of two different species, whereas at least one organism benefits. These symbiont organisms vary substantially and can include algal endosymbionts, such as zooxanthellae, anemone crabs and anemone shrimp. In specific, Symbiodinium spp. is zooxanthellae that has been investigated to establish complex relationships with sun anemones, even to the extent of coordinating cell cycles with hosts. Another endosymbiont is the Clibanarius tricolor, or the blue-legged hermit crab, which has been recorded to live in symbiosis in the Caribbean and Indo-Pacific Regions. This crab uses the surface of the anemone as a “microhabitat” and is protected from the anemone's harmful toxins by removable coverings on the surface of their bodies. Another largely-studied endosymbiont is the anemone shrimp. Hayes et al. reported cohabitation of sun anemones by Periclimenes rathbunae, also called sun anemone shrimp, in a random manner that may be directly influenced by anemone size in the West Indies. In a further study, Periclimenes yucatanicus, or spotted cleaner shrimp, were additionally observed in symbiosis with S. helianthus in the Florida Bay.

Sources: en.wikipedia.org

Reference notes

isochore A large region of genomic DNA with a relatively homogeneous composition of base pairs, distinguished from other regions by the proportion of pairs that are G-C or A-T. The genomes of most plants and vertebrates are composed of different classes of GC-rich and AT-rich isochores.

== The role of specific tissues and organs in transamination == Transamination takes place in several tissues and organs, especially the liver and skeletal muscle, which work together to manage amino groups generated during amino acid catabolism. The liver is the primary site of transamination. After proteins are digested into their monomers, amino acids, these amino acids are transported to the liver. In the cytoplasm of hepatocytes, the amino groups from many amino acids are transferred to α-ketoglutarate, forming glutamate in a transamination reaction. Through this process the amino groups from different amino acids are combined into glutamate, reducing the need for multiple enzymes in subsequent elimination or biosynthetic processes. After this transamination reaction, glutamate is transported into the mitochondria, where glutamate dehydrogenase catalyzes an oxidative deamination reaction, releasing ammonium. Free ammonium is toxic to cells, so the liver rapidly converts it to carbamoyl phosphate through a reaction with bicarbonate, allowing it to enter the urea cycle for excretion. The liver also contains aspartate aminotransferase. This enzyme catalyzes a unique reaction where oxaloacetate, instead of α-ketoglutarate, serves as the amino-group acceptor. In this reaction, glutamate transfers an amino group to oxaloacetate, forming the amino acid aspartate and regenerating α-ketoglutarate. Aspartate can then enter the urea cycle, where it combines with citrulline. Skeletal muscles is another site of transamination.

its speed. On this basis, du Châtelet proposed that energy must always have the same dimensions in any form, which is necessary to be able to consider it in different forms (kinetic, potential, heat, ...). Engineers such as John Smeaton, Peter Ewart, Carl Holtzmann, Gustave-Adolphe Hirn, and Marc Seguin recognized that conservation of momentum alone was not adequate for practical calculation and made use of Leibniz's principle. The principle was also championed by some chemists such as William Hyde Wollaston. Academics such as John Playfair were quick to point out that kinetic energy is clearly not conserved. This is obvious to a modern analysis based on the second law of thermodynamics, but in the 18th and 19th centuries, the fate of the lost energy was still unknown. Gradually it came to be suspected that the heat inevitably generated by motion under friction was another form of vis viva. In 1783, Antoine Lavoisier and Pierre-Simon Laplace reviewed the two competing theories of vis viva and caloric theory. Count Rumford's 1798 observations of heat generation during the boring of cannons added more weight to the view that mechanical motion could be converted into heat and (that it was important) that the conversion was quantitative and could be predicted (allowing for a universal conversion constant between kinetic energy and heat). Vis viva then started to be known as energy, after the term was first used in that sense by Thomas Young in 1807.

Cytotoxic T cells (TC cells, CTLs, T-killer cells, killer T cells) destroy virus-infected cells and tumor cells, and are also implicated in transplant rejection. These cells are defined by the expression of the CD8 protein on their cell surface. Cytotoxic T cells recognize their targets by binding to short peptides (8-11 amino acids in length) associated with MHC class I molecules, present on the surface of all nucleated cells. Cytotoxic T cells also produce the key cytokines IL-2 and IFNγ. These cytokines influence the effector functions of other cells, in particular macrophages and NK cells.

Australian Rules footballer Daniel Chick elected to have his left ring finger amputated as chronic pain and injury was limiting his performance. Rugby union player Jone Tawake also had a finger removed. National Football League safety Ronnie Lott had the tip of his little finger removed after it was damaged in the 1985 NFL season.

Sources: en.wikipedia.org

Frequently asked questions

Semaglutide 与天然 GLP-1 的主要差别是什么?

差别集中在三处:第 8 位残基被非天然氨基酸取代,第 34 位换成精氨酸,第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率,侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。

受体激活后为何表现出葡萄糖依赖性?

胰岛素释放需要细胞内环腺苷酸与钙信号升高,同时依赖葡萄糖代谢产生的协同信号。血糖水平较低时协同信号不足,分泌增强有限。这一机制在降糖效果与低血糖风险之间提供了缓冲。

半衰期延长是否只归因于白蛋白结合?

白蛋白结合是主要原因,它减少肾小球滤过并保护分子免受蛋白酶降解。序列修饰带来的酶解抵抗同样不可忽略,二者共同作用。脂肪链的疏水性还会影响组织分布,但其对总半衰期的贡献程度仍在研究之中。

What is the relationship between semaglutide and native GLP-1?

It is a modified version of the natural hormone, with three amino acid changes and a fatty acid side chain added. These edits extend its half-life from minutes to about one week. The core receptor activity is retained.

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