Study of the new stability properties induced by amino acid replacement of tyrosine 64 in cytochrome c(553) from Desulfovibrio vulgaris Hildenborough using electrospray ionization mass spectrometry

Hydrogen/deuterium exchange as well as charge state distribution monitored by electrospray ionization mass spectrometry were demonstrated to be a powerful and effective new tool for probing conformational properties of proteins in solution. In this paper, the influence of single amino acid replacements on the global conformation of cytochrome c(553) from Desulfovibrio vulgaris Hildenborough using isotopic exchange monitored by electrospray ionization mass spectrometry is reported. Based on their respective charge state distributions and isotopic exchanges, we have differentiated relative stability of mutants and a ladder classification with the order being wild-type > Y64F = Y64L > Y64V > Y64A, under specific conditions of pH, is proposed. (C) 1996 Academic Press, Inc.