Abstract
Palmitoyl-CoA inhibited crude glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in the eggs of the sea urchin, Hemicentrotus pulcherrimus. Fifty percent inhibition of the glucose 6-phosphate dehydrogenase in the supernatant of unfertilized eggs was obtained with 0.43 ± 0.05 μ m palmitoyl-CoA, and of 6-phosphogluconate dehydrogenase with 4.41 ± 0.20 μ m palmitoyl-CoA. Also, these enzymes in fertilized eggs 30 min after fertilization were inhibited by palmitoyl-CoA almost as much as in unfertilized eggs. Na-Palmitate, coenzyme A, acetyl-CoA, palmitoylcarnitine, and carnitine failed to exert any inhibitory effect on the activities of these dehydrogenases. The intracellular concentration of long-chain fatty acyl-CoA in unfertilized eggs (3.08 ± 0.33 nmol/10 6 eggs) was high enough for the inhibition of these enzymes, and decreased following fertilization to a low level (1.49 ± 0.08 nmol/10 6 eggs 30 min after fertilization). Spermine and spermidine canceled the inhibition of these enzymes by palmitoyl-CoA. In view of the inhibition of glucose 6-phosphate dehydrogenase and of 6-phosphogluconate dehydrogenase by palmitoyl-CoA, these dehydrogenases in the pentose monophosphate cycle are probably inhibited in unfertilized eggs by long-chain fatty acyl-CoA and released from the inhibited state by both the decrease in the level of long-chain acyl-CoA and the increase in the level of polyamines following fertilization.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call