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Effects of monovalent cations on cytochrome P‐450 camphor evidence for preferential binding of potassium
Author(s) -
Deprez Eric,
Di Primo Carmelo,
Hui Bon Hoa Gaston,
Douzou Pierre
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)00545-1
Subject(s) - chemistry , potassium , camphor , ionic radius , cytochrome , inorganic chemistry , binding site , crystallography , dimer , ion , stereochemistry , biochemistry , organic chemistry , enzyme
Binding of monovalent cations of increasing ionic radius to ferric cytochrome P‐450 cam was measured. Potassium has the highest affinity for the cation binding site observed in the X‐ray crystallographic structure with K d cat = 12 mM, compared with the smaller cation lithium, ( K d cat = 37 mM) and the larger cation cesium ( K d cat = 20 mM). Coupling between cation binding and camphor binding is established by the observation of a linear relationship between the corresponding binding free energies. Potassium binding favours a conformational change of tyrosine 96 which increases the affinity of the protein for camphor and fully dehydrates the active site.