Effects of monovalent cations on cytochrome P-450 camphor. Evidence for preferential binding of potassium.
Binding of monovalent cations of increasing ionic radius to ferric cytochrome P-450cam was measured. Potassium has the highest affinity for the cation binding site observed in the X-ray crystallographic structure with Kdcat = 12 mM, compared with the smaller cation lithium, (Kdcat = 37 mM) and the larger cation cesium (Kd 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.
INSERM-INRA U310, Institut de Biologie Physico-Chimique, Paris, France.
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D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002164:Camphor / Q000378:metabolism; D019475:Camphor 5-Monooxygenase; D002412:Cations; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D018360:Crystallography, X-Ray; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D008094:Lithium / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000378:metabolism*; D011188:Potassium / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D002412:Cations; D002164:Camphor; D003577:Cytochrome P-450 Enzyme System; D008094:Lithium; D006899:Mixed Function Oxygenases; D019475:Camphor 5-Monooxygenase; D008274:Magnesium; D011188:Potassium; D002118:Calcium