Effect of Egg yolk and its Isolated Constituents Upon the Dehydrogenase Activity of Bovine Spermatozoa

Abstract
Addition of egg yolk to washed and unwashed spermatozoa stimulated the activity of their succinic, malic, and glyceraldehyde-3-phosphate dehydrogenases. This stimulation was thought to be beneficial to sperm survival and persistence of motility, confirming the finding that boiled milk stimulates dehydrogenase activity; whereas unboiled milk fails to do so. The dehydrogenase-stimulating factor in egg yolk was associated with the acetone-soluble portion. Cholesterol stimulated succinic dehydrogenase activity but inhibited that of the other 2 enzymes. Carotene stimulated both succinic and malic and gave variable effects upon the 3d dehydrogenase under consideration.