Ve. Bychkova et al., MOLTEN GLOBULE-LIKE STATE OF CYTOCHROME-C UNDER CONDITIONS SIMULATINGTHOSE NEAR THE MEMBRANE-SURFACE, Biochemistry, 35(19), 1996, pp. 6058-6063
Methanol-induced conformational transitions in cytochrome c have been
studied by near- and far-UV circular dichroism, Trp fluorescence, micr
ocalorimetry, and diffusion measurements. The existence of at least tw
o cooperative stages of transition has been shown. At the first stage,
the native protein is transformed into an intermediate which has only
traces of tertiary structure, but has a native-like secondary structu
re content and is relatively compact; i.e., it has properties of the m
olten globule state. On the second stage, the alcohol-induced molten g
lobule is transformed into a more helical state, typical of proteins a
t high alcohol concentrations. The conditions at which the alcohol-ind
uced molten globule exists (moderately low pH and moderately low diele
ctric constant) could be similar to those existing near negatively cha
rged membrane surfaces. Consequently, these results might explain how
the molten globule state can be achieved under physiological condition
s.