The chemistry of actinocarcin. I. Further characterization and C-terminal structure of actinocarcin.

The amino-acid composition and molecular weight of actinocarcin, and C-terminal structure of actinocarcin are reported in this paper. By STEIN-MOORE'S and ultraviolet-absorption methods, the molar ratio of amino acids in actinocarcin was determined. The N-terminal amino acids are alanine and valine. The C-terminal amino acid, determined by hydrazinolysis, is tryptophan. The molecular weight is about 11,000 as estimated by ARCHIBALD'S method and amino acid analysis. Three fragments, named BrCN-I, BrCN-II and BrCN-III, were obtained by cyanogen bromide cleavage. The structure of BrCN-III, namely the C-terminal structure of actinocarcin was determined by EDMAN degradation.