Cytochrome P450 and fluconazole. Molecular model of cytochrome P450 complexed with the anti-fungal compound fluconazole. This protein plays a crucial role in metabolism in animals (including humans), fungi, plants and bacteria. There are many different types of cytochrome P450 protein, but they all have a similar function; that of catalysing oxidation and reduction reactions. They are involved in manufacturing and breaking down hormones (such as testosterone), metabolising vitamin D and detoxifying substances (including drugs) in the liver.