Ll. Leggio et al., SOME EFFECTS OF ZONA-PELLUCIDA GLYCOPROTEINS AND SULFATED POLYMERS ONTHE AUTOACTIVATION OF BOAR SPERM PROACROSIN AND ACTIVITY OF BETA-ACROSIN, Journal of Reproduction and Fertility, 100(1), 1994, pp. 177-185
The effects of zona pellucida glycoproteins, sulfated polymers and non
-sulfated polymers on the activation kinetics of boar sperm proacrosin
to beta-acrosin have been investigated. The aim has been to understan
d more about the behaviour and function of this protein after it has b
een released from the acrosome at the time of fertilization. Purified
proacrosin was allowed to autoactivate at pH 8.0 in the presence of di
fferent concentrations of homologous zona glycoproteins, sulfated poly
mers (fucoidan, chondroitin sulfates A, B and C, dextran sulfate, poly
vinylsulfate and heparin) and non-sulfated polymers (dextran, polyviny
lphosphate and hyaluronic acid). Enzyme activity was measured against
N-benzoyl-L-arginine p-nitroanalide substrate and changes in molecular
mass of the protein monitored by SDS-PAGE. Results show that zona pel
lucida glycoproteins, fucoidan, dextran sulfate and polyvinylsulfate a
ll potentiate the conversion of proacrosin to beta-acrosin but subsequ
ently inhibit its amidase activity. Dextran, polyvinylphosphate, chond
roitin sulfates A, B and C and glucose-6-sulfate, on the other hand, e
ither have no effect on autoactivation and beta-acrosin activity, or e
nhance it slightly. SDS-PAGE analysis confirmed these observations and
further indicated that binding of sulfated polymers to proacrosin inh
ibited staining by Coomassie Blue. These results are consistent with t
he hypothesis that binding of zona pellucida glycoproteins and sulfate
d compounds to proacrosin/acrosin is stereospecific and that contact a
ctivation onto soluble 'surfaces' causes conformational changes that a
re responsible for potentiation or inhibition of activation. The impli
cations of these findings for sperm binding and penetration of the zon
a pellucida are discussed.