Neutron Activation as a Means of Detecting Phosphoryl Peptides

Abstract

AMINO-ACID sequences about “active-centre” residues, which react with organophosphorus inhibitors or which are the site of attachment of phosphate in phosphoryl-enzyme intermediates, have been a subject of interest in recent years¹. In these sequence studies inhibitor or reactant labelled with phosphorus-32 is generally used and the peptides, after degradation of the protein, are detected and distinguished from other ninhydrin-positive material by their radioactivity. Sanger and co-workers^2–5 have developed a method for the determination of sequence about a labelled residue in which the use of ninhydrin is eliminated and considerably less material is required. In their work the labelled protein is subjected to partial acid hydrolysis and the phosphoryl peptides are separated by high voltage electrophoresis on paper. The pattern of peptide bands detected by autoradiography is characteristic of the amino-acid sequence present in the protein.