Y. Petillot et al., OBSERVATION OF HOLOPROTEIN MOLECULAR-IONS OF SEVERAL FERREDOXINS BY ELECTROSPRAY-IONIZATION-MASS SPECTROMETRY, Analytical biochemistry, 228(1), 1995, pp. 56-63
Several ferredoxins containing [4Fe-4S] or [2Fe-2S] active sites have
been analyzed by electrospray-ionization-mass spectrometry. For these
acidic proteins, low pH conditions must be implemented in order to ens
ure strong signals in positive-ionization mode. Under such conditions
the iron-sulfur active sites were lost in most cases. In contrast, the
holoproteins were preserved under negative-ionization mode conditions
: they were weakly but sufficiently ionized and information about thei
r cofactor content could be obtained. The experimental conditions set
up here should provide a useful basis for the detailed characterizatio
n of more complex iron-sulfur proteins. (C) 1995 Academic Press, Inc.