Abstract
The Michaelis-Menten constant (KM) of fructose and of glucose as substrate for bull spermatozoa has been measured: fructose KM = 1.04 [image], glucose KM = 0.06 [image]. The saturation rate of fructose utilization was found to be 1.8 times that of glucose utilization. This is in general agreement with characteristics of hexokinases extracted from different sources.