Enzymic characteristics of the isoenzymes of rat epididymal neutral alpha-mannosidases and their changes during development in vivo.
Three isoenzymic species of neutral alpha-mannosidase (I, II and III) were partially purified from rat epididymis and characterized. Calcium phosphate gel preferentially adsorbed acidic alpha-mannosidase activity, thereby removing the acidic enzyme from the neutral mannosidases. The neutral enzymes, which are of cytosolic origin, require Co2+ for activity, and Mn2+ can substitute partially for Co2+. Mg2+ or Ca2+ had little effect on the activity of the isoenzymes, whereas Zn2+ (100 microM) was a potent inhibitor of the mannosidases. The Km values of mannosidases I, II and III for Co2+ were 10, 10 and 2.7 mM respectively. There was marked alteration of the specific activity of the neutral alpha-mannosidases during epididymal development in vivo. The specific activities of mannosidases I and II were relatively high in the young (24 days) rats, and during the subsequent development the specific activities decreased markedly (approx. 2-3-fold). On the contrary, mannosidase III, which showed relatively low specific activity during 24-45 days of age, increased markedly (approx. 2-fold) as the animals reached adulthood.
D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D004822:Epididymis / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008361:Mannosidases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D043323:alpha-Mannosidase
D002413:Cations, Divalent; D007527:Isoenzymes; D008361:Mannosidases; D043323:alpha-Mannosidase