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Conformation of horse heart ferricytochrome c. III. Comparative optical rotatory dispersion study of the protein with its derivative heme undecapeptide
Author(s) -
Saludjian P.,
Shechter E.
Publication year - 1967
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1967.360050610
Subject(s) - chemistry , optical rotatory dispersion , cotton effect , heme , crystallography , intermolecular force , dispersion (optics) , helix (gastropod) , hemeprotein , circular dichroism , stereochemistry , photochemistry , molecule , organic chemistry , ecology , enzyme , physics , snail , optics , biology
The optical rotatory dispersion of horse heart ferricytochrome c and of a ferri heme undecapeptide have been determined under various conditions. Analysis of the Soret region makes it possible to characterize three different states of ferricytochrome c. the native state (superposition of a negative and a positive Cotton effect); an intermediate state (single positive Cotton effect whose magnitude Δ[ M ] is equal to 55,000); a denatured state (single positive Cotton effect whose magnitude Δ[ M ] is equal to 115,000) in which compared to both the native and intermediate states a more or less important decrease in helix content is observed. The optical rotatory dispersion spectra of the Soret region of the monomeric ferri heme undecapeptide is similar to that of denatured ferricytochrome c. The multiplicity of Cotton effects observed under certain conditions for the hemopeptide is a consequence, resulting from a polymerization, of intermolecular interactions. The comparison of the optical rotatory dispersion spectra of ferricytochrome c and the ferri heme undecapeptide indicates that in the intermediate state interactions remain between the heme group and the portion of the poly pep tide chain absent in the hemopeptide. These interactions disappear in the denatured state.