Microsomal cytochromes of Candida tropicalis grown on alkanes.

A comparison of methods used in isolating microsomes and in measuring microsomal cytochrome P-450 demonstrated that separation following protoplast lysis gave the best results. By this latter technique a high amount of cytochrome P-450 (0.2-0.3 nmol/mg) was recovered but cytochrome P-420, considered as the denatured form, was absent. The alkanes specifically induce cytochromes P-450 and b5 localized on the microsomes. The denaturation in vivo of cytochrome P-450 into cytochrome P-420 even occurs during storage at 1 degree C. This degradation is increased during preparation of subcellular fractions if no preventive measures are taken.