The amino acid sequence of thymopoietin II

Abstract

The amino acid sequence of bovine thymopoietin II is presented. This T cell differentiating hormone of the thymus is a single 49 amino acid polypeptide chain of 5562 daltons. There is microheterogeneity at the C terminus with approximately two thirds of the molecules lacking the C terminal arginine found on the remaining molecules. Determination of the primary structure of thymopoietin II was facilitated by a long automated sequenator run on thymopoietin II coupled to 2-isothiocyanonaphthalene-4,8-disulfonic acid (NITC), tryptic cleavage of maleated thymopoietin II to yield the overlapping C terminal peptide, and efficient manual sequencing of this peptide using benzene extractions to minimize extractive losses of peptide.