Seasonal and sex variation in the mixed-function oxygenase system of digestive gland microsomes of the common mussel, Mytilus edulis L.

Abstract

1. Sex differences in the MFO system were minimal. 2. Coincident increases in contents of cytochrome P-450, the “416-peak” and total haemoprotein occurred in summer and early winter. 3. Changes in NADH-dependent reductase activities were similar, and distinct from those of NADPH-cytochrome c reductase and cytochrome b 5. 4. NADPH-independent 7-ethoxycoumarin O-deethylase activity changed from undectable in summer to a maximum in early winter. The increase coincided with a peak in P-450 content, the appearance of a 51.5 K d protein (SDS-PAGE), and a blue shift in the λ max of P-450. 5. The results are interpreted in terms of isozymes of P-450 and a seasonal role in endogenous monooxygenation.bl]