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The pathway of CO binding to cytochrome c oxidase Can the gateway be closed?
Author(s) -
Hill Bruce C.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01140-0
Subject(s) - cyanide , chemistry , cytochrome c oxidase , photochemistry , photodissociation , azide , ligand (biochemistry) , quantum yield , oxidase test , stereochemistry , medicinal chemistry , enzyme , biochemistry , inorganic chemistry , receptor , organic chemistry , fluorescence , physics , quantum mechanics
Addition of cyanide to the CO complex of cytochrome oxidase reduces the apparent photosensitivity of the Fe–CO bond. This effect is not seen with azide, or when cyanide is added to ferromyoglobin‐CO. It is proposed that cyanide binds to Cu B , and restricts the passage of CO out of the protein. This restriction favors geminate recombination of CO and ferrocytochrome a 3 , thereby lowering the apparent quantum yield for CO photolysis. The apparent K d of cyanide for Cu B is 15.4 mM. These data support a direct role for Cu B in ligand binding by cytochrome c oxidase.