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PHOTOOXIDATIVE AND SPECTRAL STUDIES ON CYTOCHROME c. CONFORMATIONAL CHANGES INDUCED BY BINDING OF CARDIOLIPIN
Author(s) -
Jori Giulio,
Tamburro Antonio Mario,
Azzi Angelo
Publication year - 1974
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1974.tb06521.x
Subject(s) - cardiolipin , chemistry , tryptophan , tyrosine , histidine , heme , circular dichroism , photochemistry , stereochemistry , tetranitromethane , fluorescence , crystallography , biophysics , biochemistry , amino acid , enzyme , biology , phospholipid , membrane , physics , quantum mechanics
— Binding of cardiolipin to ferrocytochrome c , to form a 4:1 molar complex, results in an approximately sixfold increase of the tryptophan fluorescence emission. Furthermore, appreciable perturbations of the circular dichroism spectrum occur in the Soret and in the far‐ultraviolet regions. The irradiation of the ferrocytochrome–cardiolipin complex at pH 8·8 with visible light leads to the photooxidative modification of histidine‐18, tyrosine‐48 and methionine‐80. Comparison of the above findings with those concerning unbound ferrocytochrome c suggests that the interaction between cardiolipin and ferrocytochrome c provokes a perturbation of the protein conformation, which possibly involves the disruption of the hydrogen bonds linking the aromatic rings of tryptophan‐59 and tyrosine‐48 with one propionic side chain of the heme.