Kinetics of the proteolytic activity of intact human spermatozoa
Mercado-Pichardo, E.; Rosado-Garcia, A.
Archivos de Investigacion Medica 6(1): 65-74
1975
ISSN/ISBN: 0066-6769 PMID: 240335 Document Number: 83089
Intact human spermatozoa free of seminal plasma and washed have a hydrolytic action on N-benzoyl-D-L-arginine-beta-naphtylamide(BANA). The kinetic properties of this enzyme activity are similar to those described with reference to acrosin, which suggests the possibility that the same enzyme is involved. The hydrolytic action on BANA can be relea sed into the medium by incubation at pH lower than 4.0 and be returned to the membrane when the pH of the medium is changed to alkaline. The release curve of the pH-dependent enzyme is similar to the titration curve of sialic acid attached to the membrane. When the enzyme is attached to the sperm membrane, its specific activity decreases, but if the spermatozoa are subjected to prior treatment with neuraminidase the membrane-enzyme affinity is inhibited. The findings show that the enzyme in the spermatozoon is ion-bound to the membrane, and that sialic acid plays a role in this bond. It is suggested that drastic treatment, such as ultrasonic waves or the use of detergents, causes a redistribtuion of specific proteins, and that copper IUDs may be effective contraceptives by inhibiting the peptidase activity of spermatozoa.