Sequence determination of a peptide with 55 amino acid residues by Edman degradation and field desorption mass spectrometry

Abstract

The amino acid sequence of a polypeptide was determined by a new method combined with field desorption (FD) mass spectrometry and Edman degradation. The polypeptide, N-terminal BrCN fragment of Streptomyces erythraeus lysozyme with 55 amino acid residues, was cleaved specifically into several peptide fragments by trypsin and chymotrypsin. The molecular weights of subpeptides were determined by FD mass spectrometry. Peptide mixtures were subjected to Edman degradation successively and PTH amino acids released were measured by high performance liquid chromatography. The amino acid sequence was calculated by a computer program from molecular weights of subpeptides and PTH amino acids.