Open AccessProbing the helical content of growth hormone-releasing factor analogs using electrospray ionization mass spectrometry
Author(s) -
Cynthia L. Stevenson,
Robert J. Anderegg,
Ronald T. Borchardt
Publication year - 1993
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1016/1044-0305(93)85029-w
Subject(s) - chemistry , circular dichroism , electrospray ionization , hydrogen–deuterium exchange , mass spectrometry , electrospray , peptide , chromatography , aqueous solution , crystallography , helix (gastropod) , analytical chemistry (journal) , organic chemistry , biochemistry , ecology , snail , biology
A series of growth hormone-releasing factor analogs have been studied by both circular dichroism and electrospray ionization mass spectrometry (ESI/MS). The peptides are 32 residues long and are known to adopt a random-coil structure in aqueous solution but become increasingly helical as the proportion of organic solvent is increased. Deuterium exchange was observed as an increase in mass of the peptide, as measured by ESI/MS. Rates of exchange were measured and half-lives calculated for analogs containing amino acid substitutions designed to promote or discourage helix formation. Exchange was slower in peptides that are helical (as shown by circular dichroism) than in randomly coiled peptides. Solution conditions that favor helix formation also produced slower exchange rates. These studies suggest that ESI/MS can provide date about the extent and stability of helix formation.