SHORT IN VITRO HALF‐LIFE OF THYMOPOIETIN 32–36 PENTAPEPTIDE IN HUMAN PLASMA

Publisher Website
Google Scholar
Abstract
Thymopoietin32-36 (TP5) is a synthetic pentapeptide that has the biological activity of its parent molecule, the 49 amino acid thymic hormone thymopoietin. Tritiated thymopoietin32-36 (3H-TP5) was prepared by reductive tritiation of dibromotyrosyl-TP5. The stability of 3H-TP5 in human plasma was studied by analyzing samples by TLC at different time points and quantitating the radioactivity associated with TP5 (Arg-Lys-Asp-Val-Tyr) and its tyrosyl-containing breakdown products (Lys-Asp-Val-Tyr, Asp-Val-Tyr, Val-Tyr, Tyr). In plasma (but not in saline) the pentapeptide was rapidly degraded (apparent t1/2 [half-life] .apprx. 30 s) with the corresponding appearance of radioactivity associated with the other tyrosyl-containing reference compounds. The pentapeptide, which is active in vivo, may rapidly trigger changes in responsive cells; sustained circulating levels may not be required for activity.