Phosphoinositide specific phospholipase C activity of goat spermatozoa in transit from the caput to the cauda epididymis.

Goat sperm lysate from cauda epididymis was incubated in the presence of [14C]phosphatidyl-choline, -ethanolamine, -inositol and diphosphatidyl-glycerol. The release of [14C]diacylglycerol from only phosphatidyl inositol confirmed the presence of phosphatidyl inositol specific phospholipase C. The enzyme activity was linear up to 1 hr of incubation at a sperm concentration of 1-10 x 10(9). It had pH optimum of 7.5 in a broad range of pH activity profile (pH 6-9). Maximum activity was observed at 8 mM calcium ion concentration. EDTA and EGTA (5 mM) did not inhibit the activity completely. A comparative study on spermatozoa and fluid from caput, corpus and cauda epididymis revealed 6.5-fold increase of activity in spermatozoa and a 4-fold decrease in case of fluid during the epididymal transit. However, the total protein content remained unchanged in fluid and decreased up to the extent of 2.4-fold in spermatozoa during this process. Thirty five percent of the caudal sperm activity was soluble and the rest was associated with head (44%), mid-piece (10%) and tail (10%).