Mammalian sperm acrosomal neuraminidases

A neuraminidase and a neuraminidase-like factor (NLF) were demonstrated for the first time in acrosomes of rabbit, bull, hamster, ram and human spermatozoa. The neuraminidase is similar to the known mammalian neuraminidases, but the NLF is unique in that it renders bound sialic acid reactive in Warren's colorimetric assay but does not release it from the macro-molecular complex. Partially purified decapacitation factor preparations that inhibit fertilization also inhibit NLF activity. The true neuraminidase activity appears to arise from NLF during purification. Cowpers gland mucin of the boar was used as substrate, and the effect of neuraminidase and NLF on this substrate was not duplicated by trypsin, α-chymotrypsin, pronase, α-amylase, lysozyme, hyaluronidase or detergents.