PURIFICATION AND PROPERTIES OF BETA-N-ACETYL-D-HEXOSAMINIDASE FROM BOAR SEMINAL PLASMA

.beta.-N-Acetyl-D-hexosaminidase was purified .apprx. 190-fold to homogeneity from boar seminal plasma. It catalyzed the hydrolysis of the p-nitrophenyl-N-acetyl derivatives of both .beta.-D-glucosaminide and .beta.-D-galactosaminide but was inactive with the o- or p-nitrophenyl glycosides of other monosaccharides. Its pH optimum was 4.5 and its KM was 1.5 mM with p-nitrophenyl-N-acetyl-.beta.-D-glucosamide as substrate. The enzyme was inhibited by mercuribenzoate compounds but not by iodoacetamide, 2,2''-dipyridyl disulfide, methylmethane thiosulfonate nor N-ethylmaleimide. The active enzyme had MW .apprx. 250,000 by Sephacryl S-300 chromatography. SDS [sodium dodecyl sulfate] electrophoresis showed single bands corresponding to subunit MW .apprx. 62,000 and 107,000 depending on whether the enzyme had been denatured in the presence of 2-mercaptoethanol or not. Apparently, the enzyme is a tetramer of identical subunits, pairs of which are held together by disulfide bonds.