Chemical studies of tissue polypeptide antigen (TPA). II. Partial amino acid sequences of cyanogen bromide fragments of TPA subunit B1.

A subunit (designated B1) of the tumor associated peptide "Tissue Polypeptide Antigen" (TPA) has been cleaved by cyanogen bromide. Some of the fragments contained TPA-activity (as measured by a standardized hemagglutination inhibition method). The fragments have been separated, and partial amino acid sequences have been determined for some of the fragments. A method for purification of the most active fragment (designated BrCN:C) has been worked out from cleavage products obtained by cleavage with cyanogen bromide of "Washed Tissue Powder". By this method fragment BrCN:C has been isolated from a pool of placentae and a pool or carcinoma tumors, and the amino acid sequences of more than 50 amino acids from the N-terminus have been determined. Fragment BrCN:C has been demonstrated from three different sources, which indicates the presence of a common part in subunit B1 independent of source.