Semaglutide

At a glance

Textbook peptide engineering

Three changes to natural GLP-1 make the difference. Aib at position 8 protects against degradation by DPP-4. Arginine instead of lysine at position 34 prevents mis-attachment. A C18 fatty acid on lysine 26 binds albumin and extends the half-life from about 2 minutes to roughly 165 hours.

Albumin binding as a depot

The fatty acid chain is attached via a γ-glutamate and two OEG linkers. This lets the peptide bind to serum albumin and be released only slowly. The principle is now being transferred to many other peptides.

Extremely well documented

Unlike most research peptides, semaglutide has a large clinical literature. It concerns the medicine in its approved form and dosing and does not transfer to research chemicals.

What it is

GLP-1 (glucagon-like peptide-1) is a hormone the gut releases after a meal. Its half-life in blood is about two minutes because it is immediately cleaved by the enzyme DPP-4 and cleared by the kidney. Semaglutide is a deliberately altered version of this hormone, designed to circumvent both of these clearance routes.

What makes it special

Semaglutide is a textbook example of rational peptide design. Knudsen and Lau (2019) describe the development in detail:

Position 8: alanine is replaced by aminoisobutyric acid (Aib). DPP-4 can no longer cleave this site.
Position 34: lysine is replaced by arginine so that the fatty acid attaches unambiguously at only one site.
Position 26: a C18 diacid is coupled to the remaining lysine via a linker. This chain binds reversibly to serum albumin, the most abundant protein in blood, and thus protects the peptide from degradation and clearance.

The result is a half-life of about one week in humans. The principle of albumin binding via fatty acids is now being applied to numerous other peptides and is an active field of peptide chemistry.

What the studies say

For semaglutide, unlike the other peptides in our range, there is a large clinical literature. It is documented in regulatory approval files and in journals. The distinction matters: these studies were conducted with pharmaceutically manufactured active ingredient in a fixed formulation and dosing. They say nothing about a research chemical and do not justify any use outside the approval.

State of evidence

Preclinical and clinical: very extensive, for the medicine. As a research chemical, semaglutide is of interest for questions of peptide design, albumin binding, receptor pharmacology and as a reference substance in analytics.

Research status

Semaglutide is approved as a medicine and available on prescription. The research chemical from PURA LABS is not a medicine, is not manufactured under pharmaceutical conditions and is intended for research use only, not for human or animal use.