This page shows some interactive JSmol views of several forms of cytochrome P-450
The first figure, [P450] shows the structure of a bacterial P-450.
It is a heme protein with a cysteine sulfur coordinated to the iron in the heme active site.
In this form the iron is low spin Fe(III) and the Fe-OH2 distance is 2.16 Å.
Note there is quite good access to this site and a vacant space near the heme.
[P450/camphor] shows the P-450 from the same bacterium with camphor in the active site.
The camphor is held in place by interactions with the protein. In some forms, P-450 binds
one particular substrate molecule, in other cases it is less specific.
[P450/nicotine] shows a human P-450 with nicotine in the substrate site. The bound water molecule is displaced
and the iron has been reduced to Fe(II), ready to react with 3O2.
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