Adenylyl Cyclase and Protein Carboxyl Methylase in Human Spermatozoa

Abstract

Adenylyl cyclase (AC) and protein carboxyl methylase (PCM) activities in human ejaculated spermatozoa were measured in 31 men being evaluated for infertility at the Infertility Clinic. The spermatozoal Mn²⁺ -sensitive AC activities ranging between zero and 1.4 nmol cyclic adenosine monophosphate (cAMP)/10⁹ cells/min, was positively correlated with motility index [% motile sperm × degree (0–4)] (r = 0.72, p < 0.05). This confirms a role for cAMP in human sperm motility. PCM activities, ranging between zero and 160 pmoles (CH₃OH/10⁹ cells/min), were significantly correlated with AC activities (r = 0.86, p < 0.001). However, PCM activities were not positively correlated with motility index (p = 0.065). PCM most probably is a factor involved in spermatozoal motility since two patients suffering necrospermia possessed spermatozoa deficient in both AC and PCM activities.

Key Words:

• Spermatozoa
• Adenylyl cyclase
• Protein carboxyl methylase