Thymosin Alpha-1: structure and analysis

What it is

Thymosin alpha-1 is a 28-amino-acid peptide with an N-terminally acetylated terminus, originally isolated from thymic tissue and produced synthetically here.

The acetylation is a defining structural feature rather than a detail: the non-acetylated 28-residue sequence is a different compound.

Despite the shared name, this peptide is unrelated in structure to thymosin beta-4, the sequence supplied as TB-500. The alpha and beta thymosins are separate families that happen to have been isolated from the same tissue.

How it is produced

Assembled by solid-phase peptide synthesis: the chain is built one residue at a time on an insoluble resin support, then cleaved from the resin, deprotected and purified — most commonly by reversed-phase high-performance liquid chromatography. The purified material is lyophilized to a dry solid.

The impurity profile that appears on a certificate is a record of where that process was imperfect: deletion sequences from an incomplete coupling, truncated chains, and species retaining a protecting group.

Confirming identity

Mass spectrometry confirms the 28-residue chain and the N-terminal acetyl group. Acetylation adds forty-two mass units, a large enough increment that acetylated and non-acetylated species are unambiguously distinguishable.

Confirming acetylation is the identity question specific to this compound, and it is a straightforward one to answer given the size of the mass shift.

Analytical considerations

At 28 residues, deletion and truncation products are the expected impurity class and are closely spaced chromatographically — the same consideration that applies to sermorelin at 29 residues.

Incomplete acetylation is the modification-specific impurity, and it is comparatively easy to resolve: capping the N-terminal amine removes a positive charge and increases hydrophobicity, so the two species separate on reversed phase as well as differing in mass.

What its certificate reports

A certificate for a lot of this material names the lot, names the issuing laboratory, and states for each parameter both the method used and the specification the result was measured against. Identity and purity are the two core results; net peptide content states how much of the fill weight is actually peptide.

A certificate belongs to a lot, not to a product line. When a new lot is released it is tested again, and the certificate published against it is that lot's certificate — a previous lot's result is never carried forward.

Research use only

This page describes structure and analysis. It makes no claim about what this compound does, and none should be inferred from it. Material is supplied for laboratory research use only: it is not a drug, food, dietary supplement, cosmetic or medical device, it is not for human or veterinary consumption, and no dosing, administration or reconstitution guidance is provided for any such use.