A practical reference on GLP-1 类似物: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-14. Anything still debated is marked as such rather than presented as settled.
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。
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.
| Property | Value | Notes |
|---|---|---|
| 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 |
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
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 is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
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.
The semaglutide sequence is a 31-residue analogue of human GLP-1, altered at three positions relative to the parent hormone. Aminoisobutyric acid replaces alanine at position 8, arginine replaces lysine at position 34, and a lipophilic diacid is attached to lysine 26 through a short linker. These features are reported consistently in the structural literature. The position 8 substitution blocks recognition by dipeptidyl peptidase-4, while the attached chain drives strong, reversible association with a carrier protein in blood.
Main course (often referred to as "the main") Side dish Dessert or snack (often commercial candy, fortified pastry, First Strike Bar, or Soldier Fuel) Crackers or bread Cheese spread, peanut butter, or jelly Powdered beverage mix (commonly a fruit-flavored drink, cocoa, protein drink powder, instant coffee or tea, sport drink, or dairy shake) Utensils (commonly just a plastic spoon, though rarely a fork and knife may also be given) Flameless ration heater Beverage mixing bag Accessory pack: Xylitol chewing gum Water-resistant matchbook Napkin / toilet paper Moist towelette Seasonings, including salt, pepper, sugar, creamer, and/or Tabasco sauce Freeze-dried coffee powder Many items are fortified with nutrients. In addition, DoD policy requires units to augment MREs with fresh food whenever feasible, especially in training environments.
=== Advantages === Users report better quality of life (QOL) compared to using other devices for administering insulin. The improvement in QOL is reported in type 1 and insulin-requiring type 2 diabetes subjects on pumps. The use of rapid-acting insulin for basal needs offers relative freedom from a structured meal and exercise regime previously needed to control blood sugar with slow-acting insulin. Programmable basal rates allow for scheduled insulin deliveries of varying amounts at different times of the day. This is especially useful in controlling events such as the dawn phenomenon resulting in fewer and less severe low blood sugar events during the night. Many users feel that bolusing insulin from a pump is more convenient and discreet than injection. Insulin pumps make it possible to deliver more precise amounts of insulin than can be injected using a syringe. This supports tighter control over blood sugar and hemoglobin A1c levels, reducing the chance of long-term complications associated with diabetes. This is predicted to result in a long-term cost savings relative to multiple daily injections. Many modern insulin pumps have a "bolus wizard" that calculates how much bolus insulin is needed, taking into account expected carbohydrate intake, blood sugar level, and still-active insulin. Insulin pumps can provide a record of insulin usage through their history menus. On many insulin pumps, this history can be uploaded to a computer and graphed for trend analysis. Neuropathy is a troublesome complication of diabetes resistant to usual treatment.
In 1771, Samuel Engel mentions, in his Traité de la nature, de la culture, et de l'utilité des pommes de terre par un ami des hommes, that half of Europeans live on bread and the other half on potatoes, and also that bread is made by mixing a third or a quarter of potato with cereal flour, which gives a dish "preferred by taste, to bread of pure wheat". He refers to various authors, including François Mustel who wrote Mémoire sur les pommes de terre et sur le pain économique. Mustel invented, before 1766, a kind of inverted jointer plane to grate potatoes, peeled or not, into a fine mush that must be mixed with wheat flour: the proportion of one 1/3 flour to 2/3 potatoes gives an edible bread he says, 50% of each ingredient a good one, and at the rate of 2/3 to 1/3, it is difficult to notice that the bread is not pure wheat; the mixture must be kneaded with ordinary sourdough, but less water is used and less heat is applied, which produces an additional saving; this bread keeps fresher for longer, it remains edible for fifteen days, instead of six for traditional bread. This prolongation of freshness, which is very appreciable, encourages many Ardennes farmers to add to their bread, until the 1980s, some 10% of potatoes, the Gaumais going up to 50%. Research on the use of the tuber for bread making was numerous in France at the end of the 18th century, but this did not lead to the massive perpetuation of this practice.
=== Further reading === The Eighth Day of Creation: Makers of the Revolution in Biology. Touchstone Books, ISBN 0-671-22540-5. 2nd edition: Cold Spring Harbor Laboratory Press, 1996 paperback: ISBN 0-87969-478-5. Micklas, David. 2003. DNA Science: A First Course. Cold Spring Harbor Press: ISBN 978-0-87969-636-8. Rasmussen, Nicolas, Gene Jockeys: Life Science and the rise of Biotech Enterprise, Johns Hopkins University Press, (Baltimore), 2014. ISBN 978-1-42141-340-2. Rosenfeld, Israel. 2010. DNA: A Graphic Guide to the Molecule that Shook the World. Columbia University Press: ISBN 978-0-231-14271-7. Schultz, Mark and Zander Cannon. 2009. The Stuff of Life: A Graphic Guide to Genetics and DNA. Hill and Wang: ISBN 0-8090-8947-5. Watson, James. 2004. DNA: The Secret of Life. Random House: ISBN 978-0-09-945184-6.
Leaching involves the use of aqueous solutions to extract metal from metal-bearing materials. The extracting solution is called a lixiviant. The lixiviant is optimized in terms of pH, oxidation-reduction potential, presence of chelating agents, and temperature. In a simple implementation, a slurry of the pulverized ore in the lixiviant solution is filtered to yield a solution containing the metal ion(s) of interest. For example copper in its carbonate minerals such as malachite dissolve in aqueous sulfuric acid. On the other hand, copper sulfide minerals, which are more prevalent, are not amenable to hydrometallurgy, at least until they have been roasted. Hydrometallurgy is used to extract rare earths. By using chelating agents, one can selectively extract certain metals.. Some leaching reactor configurations are in-situ, heap, vat leaching, tank, and autoclave. In-situ leaching is also called "solution mining" involves pumped extracting solution into the deposit. The Beverley uranium deposit is an example of in-situ leaching. In heap leaching, crushed (and sometimes agglomerated) ore is piled in a heap on top of an impervious sheet. Leach solution is sprayed over the top of the heap and allowed to percolate downward through the heap. The heap design usually incorporates collection sumps, which allow the "pregnant" leach solution (i.e. solution with dissolved valuable metals) to be pumped for further processing.
Sources: en.wikipedia.org
=== Research environment === In the United States, research in digital agriculture is primarily funded by the National Institute of Food and Agriculture (NIFA) which comes under the US Department of Agriculture and to a lesser extent, by the National Science Foundation. Two large institutes applying IoT or artificial intelligence in digital agriculture have been unveiled by these funding organizations working together.
== SJ == SJ (s) Svalbard and Jan Mayen (ISO 3166 digram) (i) Societas Iesu (Latin: The Society of Jesus, the Jesuit order) (i) Statens Järnvägar (Swedish State Railways) SJA – (i) Staff Judge Advocate (military law) SJC – (i) Supreme Judicial Court of Massachusetts (note: the highest court in the state of Maine is also called the Supreme Judicial Court) SJM – (s) Svalbard and Jan Mayen (ISO 3166 trigram) SJW – (i) Social Justice Warrior
Working at the Royal Society in the 1660s, the physician Richard Lower began examining the effects of changes in blood volume on circulatory function and developed methods for cross-circulatory study in animals, obviating clotting by closed arteriovenous connections. The new instruments he was able to devise enabled him to perform the first reliably documented successful transfusion of blood in front of his distinguished colleagues from the Royal Society. According to Lower's account, "...towards the end of February 1665 [I] selected one dog of medium size, opened its jugular vein, and drew off blood, until its strength was nearly gone. Then, to make up for the great loss of this dog by the blood of a second, I introduced blood from the cervical artery of a fairly large mastiff, which had been fastened alongside the first, until this latter animal showed ... it was overfilled ... by the inflowing blood." After he "sewed up the jugular veins", the animal recovered "with no sign of discomfort or of displeasure". Lower had performed the first blood transfusion between animals. He was then "requested by the Honorable [Robert] Boyle ... to acquaint the Royal Society with the procedure for the whole experiment", which he did in December 1665 in the Society's Philosophical Transactions. The first blood transfusion from animal to human was administered by Jean-Baptiste Denys, eminent physician to King Louis XIV of France, on June 15, 1667. He transfused the blood of a sheep into a 15-year-old boy, who survived the transfusion.
Chargaff's rules A set of axioms which state that, in the DNA of any chromosome, species, or organism, the total number of adenine (A) residues will be approximately equal to the total number of thymine (T) residues, and the number of guanine (G) residues will be equal to the number of cytosine (C) residues; accordingly, the total number of purines (A + G) will equal the total number of pyrimidines (T + C). These observations illustrate the highly specific nature of the complementary base-pairing that occurs in all duplex DNA molecules: even though non-standard pairings are technically possible, they are exceptionally rare because the standard ones are strongly favored in most conditions. Still, the 1:1 equivalence is seldom exact, since at any given time nucleobase ratios are inevitably distorted to some small degree by unrepaired mismatches, missing bases, and non-canonical bases. The presence of single-stranded DNA polymers also alters the proportions, as an individual strand may contain any number of any of the bases.
Dual Recombinase technology can be used to induce multiple conditional mutations to study the diseases which manifest as a result of simultaneous mutations in multiple genes. Certain inteins have been identified which splice only at certain permissive temperatures, leading to improper protein synthesis and thus, loss-of-function mutations at other temperatures. Conditional mutations may also be used in genetic studies associated with ageing, as the expression can be changed after a certain time period in the organism's lifespan. Replication timing quantitative trait loci affects DNA replication.
Sources: en.wikipedia.org
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。
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。
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。
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and neutral endopeptidases. Semaglutide carries a non-natural amino acid at position eight that blocks that cleavage, and a fatty diacid side chain that binds albumin. The result is a much longer duration of action than the native hormone.