What is peptide?

01

What it is

The sequence is Gly–Glu–Pro–Pro–Pro–Gly–Lys–Pro–Ala–Asp–Asp–Ala–Gly–Leu–Val. The reference structure has the molecular formula C62H98N16O22 and a molecular weight of 1419.5 g/mol (PubChem CID 9941957).

Papers often call it a stable gastric pentadecapeptide. Pentadecapeptide simply means a chain of 15 amino acids.

Sources: [3] PubChem · reference structure · [4] Frontiers in Pharmacology · 2021

02

Where it came from

In 1993, Predrag Sikirić’s group in Zagreb described a protein from human gastric juice and proposed a role for it in protecting the stomach lining. Follow-up papers in 1994 studied a 15-amino-acid fragment of that protein: the sequence sold under this name today.

Most published research still comes from that group and its collaborators. A 2025 review notes that most of the evidence comes from animal studies, and a 2025 literature and patent review traces how the research and patents developed.

Sources: [1] Journal of Physiology (Paris) · 1993 · [2] Life Sciences · 1994 · [7] Current Reviews in Musculoskeletal Medicine · 2025 · [8] Pharmaceuticals · 2025

03

What researchers have studied

The literature is large and mostly preclinical. The main themes:

• Gastrointestinal research in rodent models, where the peptide was first studied.
• Tendon and ligament research, including a 2011 study of tendon cells in culture.
• Blood-vessel growth factors and related signaling.

These are observations in laboratory models. They are not evidence about any use in people.

Sources: [2] Life Sciences · 1994 · [5] Journal of Applied Physiology · 2011 · [6] Current Pharmaceutical Design · 2018

04

vs

The two are often sold and studied together, but they are unrelated molecules. is a fragment of a gastric-juice protein with one well-defined sequence. is named after thymosin beta-4, a 43-amino-acid actin-binding protein found in most cells, and the name is used for more than one thymosin-derived sequence. Their research themes differ too: gastrointestinal and tendon models on one side, blood-vessel development and cell migration on the other.

Prism Labs sells each on its own and together as the . Side by side: vs .

Sources: [1] Journal of Physiology (Paris) · 1993 · [9] PNAS · 1981 · [10] Annals of the New York Academy of Sciences · 2007

05

How it is supplied and stored

ships as a lyophilized (freeze-dried) powder in 5 mg or 10 mg vials. The powder is stable at room temperature in transit. For lab use it is reconstituted with bacteriostatic water such as .

For a vial, concentration is content divided by volume: 10 mg in 2 mL gives 5 mg per mL. The reconstitution calculator handles other combinations.

For storage before and after reconstitution, see how to store lyophilized peptides.

06

How to verify a batch

Every lot has its own certificate of analysis from an independent lab. Read three results separately:

• Identity: confirms the expected compound was detected.
• Purity: the share of the measured material that is the intended compound.
• Content: the amount measured, compared with the label.

Then match the lot number on your vial or bottle to the report, and use the report’s verification link to confirm it with the testing lab. Step by step: how to read a peptide COA.