Über die Struktur der Protamine. II. Strukturaufklärung des Clupeins. (Sechste Mitteilung über enzymatische Proteolyse

Abstract

Clupein, containing 15 amino acids of which 10 are arginine, was acted upon by protaminase, 2 arginine residues being removed from the carboxyl end of the molecule. The product was clupean. Enzymatically pure trypsin split 4 linkages in clupean, yielding 3 tripeptides and a dipeptide. The tripeptides, as detd. by fractional enzymatic degradation, had arginine residues in the amino and carboxyl positions, with a monoamino acid between. The monoamino acid in one of the tripeptides was proline. Enzymatic analysis of the dipeptide fraction showed that there was present 1 molecule of arginyl-monoamino acid, and 1 molecule of monoaminoacyl-arginine. Neither of the monoamino acids was proline. Therefore the structure of clupein very probably is M-A-A-M*-A-A-M*:A-A-M*-A-A-M-A-A, where A is an arginine residue and M is a monoamino acid. One of the 3 monoamino acids marked with an asterisk is proline.