Thymosin Alpha-1 RGDR

1 Identity

Synthetic 36-residue fusion peptide: thymosin alpha-1 (28 residues, N-terminally acetylated) plus a GGGG linker (4 residues) plus an RGDR targeting motif (4 residues), fused at the C-terminus. Sold by one seller as "TA1-RGDR", whose own page title and page address spell it "RDGR" — a transposition that would be a different and non-functional peptide.

Sequence

Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-Gly-Gly-Gly-Gly-Arg-Gly-Asp-Arg. The C-terminal arginine is the PHARMACOPHORE: RGDR is a CendR motif whose free C-terminal arginine is required for neuropilin-1 binding. Fuse it at the N-terminus instead, or add any residue after the terminal Arg, or deliver it as the C-terminal amide, and the motif is abolished while the composition is unchanged.

Molecular formula

The seller'S stated formula is wrong and chemically impossible. One seller prints C167H279N49O67S, which contains one sulfur atom — but the disclosed sequence contains no cysteine and no methionine. Thymosin alpha-1 has neither, and neither GGGG nor RGDR contributes sulfur. There is no sulfur in this molecule. The carbon and nitrogen counts are also wrong against the sequence. The hedge "(approximate)" does not rescue it: a molecular formula is an integer atom count, and "approximately one sulfur atom" is not a meaningful statement. This company does not adopt the seller's formula and does not substitute its own without a measured determination. The impossible formula is printed here verbatim rather than corrected in silence, because the fact that a seller published it is information a buyer needs.

Average mass

Approximately 3821 Da, which IS correct — thymosin alpha-1 at 3108.3 plus GGGG at 228.2 plus RGDR at 484.5. The diagnostic pattern is worth naming: the mass follows correctly from the sequence, while the formula was attached from somewhere else.

Monoisotopic mass

Not available from an authoritative source.

Salt / variant note

Thymosin alpha-1 itself, already in this catalog — the 28-residue parent. The critical collision: RGDR and RDGR are ANAGRAMS with identical exact mass and identical HPLC behavior. A preparation of Ta1-GGGG-RDGR passes every test the seller advertises and is inert at neuropilin-1. The seller's own page renders the name both ways. Also the C-terminal amide against the free acid, a 1 Da difference that determines whether the CendR motif functions at all.

2 Class & testing panel

Form

Single article

Testing panel

Special-class panel — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

The construct's design is published in a peer-reviewed source, ACS Omega 2020, and the seller's description matches it. What is unverified is whether the vial contains the 36-mer, and the seller's published chemistry gives reason to doubt it.

4 Storage & specification

Storage

Lyophilized, -20 degrees C plus or minus 5 degrees C, desiccated, protected from light.

Shelf life

Not assignable without measured data.