title: Short in vitro half-life of thymopoietin32--36 pentapeptide in human plasma.
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 (3 /-TP5) was prepared by reductive tritiation of dibromotyrosyl-TP5. The stability of 3 H-TP5 in human plasma was studied by analyzing samples by thin-layer chromatography 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 approximately 30 seconds) with the corresponding appearance of radioactivity associated with the other tyrosyl-containing reference compounds. These data imply that the pentapeptide, which is active in vivo, may rapidly trigger changes in responsive cells; sustained circulating levels may not be required for activity.
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D002855:Chromatography, Thin Layer; D006207:Half-Life; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D016305:Thymopentin; D013946:Thymopoietins / Q000097:blood*; D013951:Thymus Hormones / Q000097:blood*
chemical_list: D010446:Peptide Fragments; D013946:Thymopoietins; D013951:Thymus Hormones; D016305:Thymopentin