Shedding of gACE from residual body membrane of rat sperm.

Germinal angiotensin I-converting enzyme (gACE) is expressed only in the testis and is uniquely present in developing spermatids and sperm. We previously purified soluble gACE from porcine seminal plasma, and reported that gACE was secreted from residual body on spermatozoa by the other peptidase(s), namely Sheddase. Using Nma/DNP substrate, it was observed that the shedding activity in testicular fluid was stronger than in the sperm membrane and epididymal fluid. The shedding activity was inhibited by AEBSF and antipain, and not by EDTA and E-64. Accordingly, it is thought that Sheddase is an endo-type of serine peptidase.