Active Site Phosphopeptides from Pea Seed Nucleoside Diphosphate Kinase

Abstract

Nucleoside diphosphate kinase from pea seed was incubated with (³²P)ATP, inactivated with alkali and digested with trypsin. From the digest the main part of the bound phosphorus was isolated as two phosphopeptides, both containing 14 amino acid residues. These phosphopeptides had an identical amino acid sequence Asx-Val-Ile-His-Gly-Ser-Asx-Ala-Val-Glx-Ser-Ala-Asx-Lys, as determined by dansyl-Edman technique. The only difference found between the two phosphopeptides was a different lability to acid of the phosphoryl bond. The possibility that the appearance of two phosphopeptides was due to a specific migration of the phosphoryl bond within the peptide chain from 1-phosphohistidine to 3-phosphohistidine is discussed.