Thymulin (CAS 63958-90-7), also known as Facteur Thymique Serique (FTS) or Serum Thymic Factor, is a synthetic nonapeptide metallopeptide with a molecular weight of 952.21 g/mol in its zinc-complexed form. Defined by the amino acid sequence pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn, Thymulin features an N-terminal pyroglutamyl residue and requires the coordination of a single zinc ion (Zn2+) for biological activity, a structural requirement that distinguishes it from other thymic peptides. This zinc dependency makes Thymulin one of the few naturally occurring metallopeptide hormones in the endocrine system. Produced via solid-phase peptide synthesis, Thymulin is associated with T-cell differentiation and thymic endocrine signalling.

Thymulin is a thymic hormone whose circulating concentrations correlate with zinc status in experimental models. In vitro studies have examined the zinc-dependent conformational transition underlying Thymulin activity, with research documenting that chelation of metal ions abolishes the biological activity of the serum thymic factor and that zinc restores it, establishing it at the required 1:1 metal-to-peptide molar ratio and forming the basis for the designation of the zinc-complexed form as “thymulin” [1]. In vivo rodent studies have examined circulating Thymulin concentrations in relation to zinc status, thymic involution, and age-related immune function changes, with published research documenting that oral zinc supplementation in aged mice restores active (zinc-saturated) thymulin, induces thymic regrowth, and partially restores peripheral immune function, and characterising the age-related decline as a defect in the zinc saturation of thymulin rather than in its synthesis or secretion [2], making Thymulin a reference compound in thymic peptide research examining the interplay between zinc coordination, metallopeptide hormone activity, and age-related thymic endocrine function.

Thymulin is manufactured in a cGMP compliant laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

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