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Cytochrome P450cams are a type of p450 enzyme that adds oxygen to camphor. Camphor is a toxic to cells and acts in a way similar to a muscarinic receptor agonist. The addition of oxygen to camphor inhibits its activity. p450cam is a monomer with 414 amino acids.


1. Here the enzyme is shown in its entirety. It is drawn in the same way as on the previous page with alpha helices in pink, beta sheets in yellow, and regions without secondary structure in white. The Heme, CO, Camphor and Cys357 are drawn in wireframe.
  2. Here only the Heme, CO, Camphor and Cys357 are drawn in wireframe in order to better see the active site. Note that the carbon monoxide is bound to one side of the iron while Cysteine 357 is bound to the other side. The presence of Carbon monoxide prevents the action of the P450cam upon it's substrate, camphor.
  3. The same reaction in the absense of carbon monoxide allows the binding of oxygen, allowing p450cam to add it to camphor, the completed process shown here, with the product 5-Exo-Hydroxycamphor shown. 


1, 2. Raag R, Poulos TL. Crystal structure of the carbon monoxide-substrate-cytochrome P-450CAM ternary complex.
Biochemistry. 1989 Sep 19; 28 (19);7586-92. (PubMed)

    3CPP(PDB) Pseudomonas putida

3. Li, H. Narasimhulu, S. Havran, L.M., Winkler, J.D., Poulos, T.L. Crystal structure of cytochrome P450-CAM complexed with its catalytic product, 5-Exo-Hydroxycamphor
  J.Am.Chem.Soc. 1995 117: 6297-6299. (Citation)

    1NOO(PDB) Pseudomonas putida

Image from Kamachi T, Yoshizawa K. A Theoretical Study on the Mechanism of Camphor Hydroxylation by Compound I of Cytochrome P450 

J. Am. Chem. Soc., 2003, 125 (15), pp 4652–4661. (Citation)

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