Structural and sequencing studies on peptides, proteins, and glycopeptide antibiotics by mass spectrometry

Abstract

-Mass spectrometry is now established as a useful method for establishing the sequence of small peptides (2-10 residues), following their derivatisation (by N-acetylation and permethylation) to increase volatility.The strength of the method lies in its ability to deal with simple mixtures of peptides and to identify unusual amino acids.The weakness of the method (relative to some wet-chemical approaches to sequencing) lies in the current inability of the method to sequence larger peptides, and the relatively low sensitivity when working with peptides near the molecular weight limit of the method.This last shortcoming is due to our present inability to volatilise and efficiently produce high mass ions from the larger peptides, the inherent sensitivity of mass spectrometry being in contrast extremely high.The use of deuterated reagents in degradation and derivatisation reactions provides a powerful method for structure elucidation of glycopeptide antibiotics containing unusual amino acids.

Electron impact and methane, isobutane and ammonia chemical ionization mass spectra of peptide amides related to melanostatin (Pro-Leu-Gly-NH2)

“…75 (100) 282 (5) 75 (18) 281 (4 89 (4) 282 (21 89 (100) 282 (2) 89 (41 1 282 (1) 103 (100) 282 (1 1 103 (63) 321 (-) 115 (2) 322(2) 115(100) 322 (2) 115 (100) 281 (-1…”