On the role of fumarate reductase in anaerobic carbohydrate catabolism of Mytilus edulis L

Abstract

1. 1. The role of the fumarate:NADH oxidoreduction in the anaerobic glycolysis of the sea mussel is examined and discussed.

2. 2. Fumarate reductase activity is present in submitochondrial particles especially from adductor muscle, digestive gland and mantle.

3. 3. The pH optimum of the enzyme complex is 7.9; the approx Km's for NADH and fumarate are 4.0 × 10−5 M and 6.3 × 10−5 M, respectively.

4. 4. The enzyme complex is inhibitied by amytal, antimycin, ethanol, malonate, phosphate, rotenone, and succinate, and stimulated by Mg2+.

5. 5. It is concluded that part of the mitochondrial respiratory chain is involved in the reduction of fumarate by NADH, comprising site 1 of the oxidative phosphorylation.