Cobalt-substituted cytochrome P-450cam.
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Reconstitution of the apo-cytochrome with cobalt protoporphyrin provides a faithful P-450cam analogue as characterized by optical, ligand-binding, and enzymatic parameters. The thiol and cyanide complexes exhibit Soret "hyper" spectra, not previously observed in cobalt porphyrins. Substrate-induced spectral changes and limited stereospecific hydroxylation activity are retained in the cobalt P-450cam. The EPR (electron paramagnetic resonance) spectra of the reduced cobaltous protein indicate clearly an endogenous axial ligand other than a nitrogenous base and support an assignment of thiolate coordination. A thiolate ligand is also indicated by EPR measurements in the oxygenated cobaltous analogue. By analogy, these studies suggest that the native ferrous and oxygenated P-450cam states retain a thiolate axial ligand.
author list (cited authors)
Wagner, G. C., Gunsalus, I. C., Wang, M. Y., & Hoffman, B. M
complete list of authors
Wagner, GC||Gunsalus, IC||Wang, MY||Hoffman, BM