Biochemistry and Molecular Biology International 1995-04-01

The use of FAB mass spectrometry and pyroglutamate aminopeptidase digestion for the structure determination of pyroglutamate in modified peptides.

J Kim, K Kim

Index: Biochem. Mol. Biol. Int. 35(4) , 803-11, (1995)

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Abstract

A new method for the determination of the modified amino acid structures of peptides containing pyroglutamyl residue in their N-terminal position is reported. The combination of fast atom bombardment (FAB) mass spectrometry and pyroglutamate aminopeptidase digestion provides a convenient and sensitive method for the identification of pyroglutamate. In order to investigate the nature of the amino terminal region of the follow post-translationally modified peptides containing pyroglutamyl residues, Neurotensin, Hypertrehalosaemic neuropeptide, and Luteinizing Hormone Releasing Hormone (LH-RH) were digested with pyroglutamate aminopeptidase and analyzed by FAB mass spectrometry. The method provided direct information about the N-terminal structure. The N-terminal pyroglutamates of these peptides are unequivocally determined at a level of 0.9-2.8 nmol per peptide. Several of the complicated procedures and controversies, which accompany the application of traditional methods, are eliminated. We describe the advantages of the combination procedure of FAB mass spectrometry and pyroglutamate aminopeptidase digestion for modified amino acid determination.