The enzyme that inactivates native GHRH almost instantly, and how one acyl group defeats it

Published 26 October 2026 · REVIVE LAB UAE Research Desk · 5 min read
Dipeptidyl peptidase 4 is a membrane and plasma enzyme that removes two residues from the amino terminus of peptides whose second residue is alanine or proline. Native GHRH begins tyrosine-alanine, so the enzyme cleaves it to GHRH 3-44, which does not activate the receptor, and the native hormone has a circulating half-life of a few minutes — Frohman and colleagues characterised this in the mid-1980s. Tesamorelin carries a hexenoyl group on the tyrosine amino group, which the enzyme cannot accommodate, and its half-life is in the range of twenty-six to thirty-eight minutes. The same enzyme inactivates GLP-1, and the same problem shaped that drug class.

The enzyme

Dipeptidyl peptidase 4, also known as CD26, is expressed on endothelium, kidney, intestine and lymphocytes and circulates in soluble form. It is a serine protease with strict specificity for a proline or alanine at position 2 and a free amino terminus. Many peptide hormones fit — GLP-1, GIP, GHRH, substance P, several chemokines — which is why the enzyme is a drug target in its own right for diabetes.

Inhibitors of the enzyme, the gliptins, raise native GLP-1 and also, incidentally, native GHRH.

The cleavage and the protection

GHRH 3-44 retains most of the sequence but lacks the tyrosine that the receptor requires, so it is not just weaker but inactive, and it may occupy the receptor without signalling. Blocking the amino terminus with any acyl group prevents enzyme binding; the hexenoyl group was chosen as the smallest that gave full protection while preserving receptor affinity. The half-life extension is about tenfold, enough for a practical pharmacology, not enough for a long-acting profile.

CJC-1295, a different analogue, adds amino acid substitutions and an albumin-binding group to go further.

Why it is here

Because the one modification that defines tesamorelin exists to defeat this enzyme, and the half-life is part of the established pharmacology. It describes chemistry and no use of the pack.

Tesamorelin is supplied by REVIVE LAB UAE for laboratory research use only, with identity by mass spectrometry and purity by HPLC for the batch. It is not for human or veterinary use, and no dosing, administration or protocol guidance is provided.

What it costs

FormatStrengthPriceAvailability
Tesamorelin Pack20 mgAED 1010In stock

Delivery is AED 40 flat and free on orders over AED 700. Payment is cash on delivery anywhere in the UAE, or USDT (TRC20) in advance, which takes 5% off the order total.

Frequently asked

The enzyme?

Dipeptidyl peptidase 4, also known as CD26, is expressed on endothelium, kidney, intestine and lymphocytes and circulates in soluble form. It is a serine protease with strict specificity for a proline or alanine at position 2 and a free amino terminus. Many peptide hormones fit — GLP-1, GIP, GHRH, substance P, several chemokines — which is why the enzyme is a drug target in its own right for diabetes.

Does REVIVE LAB UAE provide dosing guidance?

No. REVIVE LAB UAE supplies research materials and provides no dosing, administration or protocol guidance of any kind. Every product is sold for laboratory research use only and is not for human or veterinary consumption.

How fast is delivery in the UAE?

Stock is held in Dubai. An order confirmed before 4 PM Dubai time is dispatched the same working day, reaching Dubai and Abu Dhabi the same day and the remaining emirates within 24 hours. Delivery is AED 40 flat and free over AED 700.

Tesamorelin Pack — in stock, dispatched from Dubai
HPLC-verified, lot certificate on every carton, 24-hour delivery nationwide. Browse the catalogue → All peptides UAE

Related reading

Supplied for laboratory research use only. Not for human or veterinary consumption. REVIVE LAB UAE provides no dosing, administration or protocol guidance.