Sperm hyaluronidase activation by purified predominant and major basic human seminal coagulum proteins

This study demonstrated that semenogelin I and II, the predominant and the major basic human seminal coagulum proteins respectively were shown to be potent activators of sperm hyaluronidase. These proteins stimulated the activity of bovine testicular hyaluronidase, goal cauda sperm hyaluronidase and human ejaculated sperm hyaluronidase. Human seminal plasma protein, which predominantly contains the basic degradation residues of the basic coagulum proteins and albumin (pI 4.7) and which is also basic at the assay pH 3.8, also showed activation of bovine testicular hyaluronidase while acidic pepsin (pI < 1.0) exhibited no such activation. The findings may be utilized as an assay method for comparative evaluation of specific activation units of the purified basic seminal coagulum proteins or their cleavage products and for quantifying the total basic protein (pI > 3.8) units in human seminal plasma. One unit of the coagulum protein was defined as the amount of the activator that increases 1 mIU of hyaluronidase activity by 50%. The specific activity of the 57 kDa and 75-79 kDa coagulum proteins, and that of serum albumin against Sigma bovine testicular hyaluronidase (type IV), were 11,447, 8600 and 6252 units per mg protein respectively. It was speculated that human seminal coagulum proteins may have an activation effect on spermatozoal hyaluronidase activity in vivo.