This is a working overview of fatty diacid chain, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-16 and is reviewed periodically as new material appears.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L-cells after food intake. It contains 31 amino acids and differs from native GLP-1 through modifications that slow enzymatic breakdown. The peptide was developed to extend the short circulating half-life of endogenous GLP-1, which is measured in minutes. Researchers introduced the compound in the early 2010s. Two backbone changes and a fatty acid side chain define its structure, distinguishing it from earlier GLP-1 receptor agonists.
The compound binds the GLP-1 receptor on pancreatic beta cells and other tissues, activating a G-protein signaling cascade that raises intracellular cyclic AMP. This action increases glucose-dependent insulin secretion when blood glucose is elevated, while binding also slows gastric emptying and reduces glucagon release. In the central nervous system, receptor activation in the hypothalamus and brainstem contributes to reduced appetite. The fatty acid chain binds albumin, which protects the peptide from renal filtration and enzymatic degradation. This albumin binding is central to its extended circulation time.
Native GLP-1 is degraded rapidly by dipeptidyl peptidase-4. Semaglutide resists this cleavage because alanine at position 8 is replaced by alpha-aminoisobutyric acid. A second substitution at position 34 introduces arginine, which further stabilizes the peptide. The most distinctive modification is a spacer and C18 fatty diacid attached at lysine 26, enabling strong albumin affinity. These three changes together produce a half-life measured in days rather than minutes, and the same structural logic underlies other long-acting analogs in this class.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Pulse oximetry is a method used to estimate the percentage of oxygen bound to hemoglobin in the blood. This approximation to SaO2 is designated SpO2 (peripheral oxygen saturation). The pulse oximeter is a small device that clips to the body (typically a finger, an earlobe or an infant's foot) and displays its reading, or transfers it to another device. Oxygenated and deoxygenated hemoglobin differ in absorption of light of different wavelengths. The oximeter uses light-emitting diodes of different wavelengths in conjunction with a light-sensitive sensor to measure the absorption of red and infrared wavelengths in the extremity, and estimates the SpO2 from the absorption spectrum.
=== Synthesis of peptides === Another common example is the reaction of a primary amine or secondary amine with a carboxylic acid or with a carboxylic acid derivative to form an amide. This reaction is widely used, especially in the synthesis of peptides. On the simple addition of an amine to a carboxylic acid, a salt of the organic acid and base is obtained. To overcome this, the carboxylic acid first needs to be "activated". This is usually done by converting the acid into a more reactive derivative (i.e. anhydride, acid halide) or by using a coupling agent. In some cases, high temperatures (>200 °C) can overcome salt formation by driving off water, without the need for "activation" of the carboxyl group. The downside to this simple reaction is that the compounds may decompose at these elevated temperatures. The carboxylic acid derivatives can be esters, anhydrides, acid halides or any other activated species. The choice of activated carboxyl group or coupling agent can be very important in peptide synthesis, as using the wrong one can lead to racemization.
The catalytic domain of MMP-3 can be inhibited by tissue inhibitors of metalloproteinases (TIMPs). The n-terminal fragment of the TIMP binds in the active site cleft much like the peptide substrate would bind. The Cys1 residue of the TIMP chelates to the catalytic zinc and forms hydrogen bonds with one of the carboxylate oxygens of the catalytic glutamate residue (Glu202, see mechanism below). These interactions force the zinc-bound water molecule that is essential to the enzyme's function to leave the enzyme. The loss of the water molecule and the blocking of the active site by TIMP disable the enzyme. The hemopexin-like domain of MMPs is highly conserved and shows sequence similarity to the plasma protein, hemopexin. The hemopexin-like domain has been shown to play a functional role in substrate binding and/or in interactions with the tissue inhibitors of metalloproteinases (TIMPs), a family of specific MMP protein inhibitors.
Sources: en.wikipedia.org
== Asia == Asian countries are the primary destination for crude oil from the Gulf, with most of it travelling via the Strait of Hormuz. In 2024, around 84 per cent of the crude oil and 83 per cent of LNG passing through the Strait went to Asia; nearly 70 per cent of the oil went to China, India, Japan, and South Korea. Governments and businesses across the region have been imposing measures to reduce the impact of the fuel crisis, and among the worst hit countries in the region include Pakistan, Bangladesh, and Vietnam.
frequent blood glucose monitoring (8–10 times daily); continuous blood glucose monitoring; logging and review of blood glucose values, searching for patterns of low blood sugar values; conservative increases in insulin delivery; awareness to the signs of hypoglycemia; awareness to hyperglycemia in response to increased delivery of insulin; use of appropriate types of insulin (long-acting, short-acting, etc.) in appropriate amounts.
==== Antarctic plate ==== Marion hotspot (25) 46°54′S 37°36′E, w= 0.5 az= 080° ±12° Crozet hotspot (52) 46°06′S 50°12′E, w= 0.8 az= 109° ±10° rate= 25 ±13 mm/yr Possibly related to the Karoo-Ferrar geologic province (183 Ma) Kerguelen hotspot (20) 49°36′S 69°00′E, w= 0.2 az= 050° ±30° rate= 3 ±1 mm/yr Related to the Kerguelen Plateau (130 Ma) Heard hotspot (53), possibly part of Kerguelen hotspot 53°06′S 73°30′E, w= 0.2 az= 030° ±20° Île Saint-Paul and Île Amsterdam could be part of the Kerguelen hotspot trail (St. Paul is possibly not another hotspot) Balleny hotspot (2) 67°36′S 164°48′E, w= 0.2 az= 325° ±7° Erebus hotspot (54) 77°30′S 167°12′E
=== Radioimmunotherapy === Radioimmunotherapy (RIT) involves the use of radioactively-conjugated murine antibodies against cellular antigens. Most research involves their application to lymphomas, as these are highly radio-sensitive malignancies. To limit radiation exposure, murine antibodies were chosen, as their high immunogenicity promotes rapid tumor clearance. Tositumomab is an example used for non-Hodgkin's lymphoma.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
It is a synthetic analog of GLP-1 produced through medicinal chemistry to resist enzymatic degradation. The design goal was longer circulation than the native hormone.