Cytochrome proximal cysteine ligand

II. REPLACEMENT OF THE PROXIMAL HISTIDINE LIGAND IN Mb INTO CYSTEINE OR TYROSINE PROTEIN MIMICS OF CYTOCHROME... 

There are two types of electron transport those involving flavoproteins and iron-sulfur proteins, and those requiring only flavoproteins. The X-ray crystal structure of the soluble cytochrome P450 from Pseudomonas putida grown on camphor (P-450-CAM) has been determined (Poulos et ah, 1985), as have several others. The haem group is deeply embedded in the hydrophobic interior of the protein, and the identity of the proximal haem iron ligand, based on earlier spectroscopic studies (Mason et ah, 1965) is confirmed as a specific cysteine residue. 

The resting state, the low-spin Fe complexes of the family of monooxygenase and oxidase enzymes known as the cytochromes P450 see Iron Heme Proteins, Mono- Dioxygenases), have one cysteine thiolate as the proximal ligand T258 water molecule as the distal... 

Liu HI, Sono M, Kadkhodayan S, Hager LR Hedman B, Hodgson KO, Dawson JH (1995) X-ray absorption near edge studies of cytochrome P-450-cam, chlo-roperoxidase, and myoglobin. Direct evidence for the electron releasing character of a cysteine thiolate proximal ligand. J Biol Chem 270 10544-10550... 

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