What is DPP-4 and why is it relevant to GLP-1 research?

DPP-4 (dipeptidyl peptidase-4) is an enzyme that inactivates incretin hormones, including native GLP-1 and GIP. It is the single biggest obstacle in GLP-1 drug design.

What it does

DPP-4 cleaves two amino acids from the N-terminus of its targets. For GLP-1 that clip is enough to abolish receptor activity — the truncated peptide no longer signals. The enzyme is abundant in plasma and on endothelial surfaces, which is why native GLP-1 has a half-life of roughly two minutes.

Two ways around it

• Modify the peptide. Substitute the residue DPP-4 recognises with one the enzyme cannot cleave. This is the approach behind the modern GLP-1 analogs, and it is why they survive long enough to be dosed weekly rather than continuously.
• Inhibit the enzyme. Block DPP-4 itself so native incretins last longer. This is a separate drug class — the gliptins — that raises endogenous GLP-1 rather than supplying an analog.

Why it matters when reading a spec

A listed half-life is largely a statement about how well a compound resists this enzyme plus how strongly it binds albumin. Two analogs of the same hormone can differ by three orders of magnitude in duration for exactly these reasons.

See what GLP-1 receptor agonists are. Research use only. Not medical advice.