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 monit ored by electrospray ionization mass spectrometry were demonstrated to be a powerful and effective new tool for probing conformational prope rties 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 mo nitored by electrospray ionization mass spectrometry is reported. Base d on their respective charge state distributions and isotopic exchange s, we have differentiated relative stability of mutants and a ladder c lassification with the order being wild-type > Y64F = Y64L > Y64V > Y6 4A, under specific conditions of pH, is proposed. (C) 1996 Academic Pr ess, Inc.