Sialyl- and galactosyltransferases in the human chorionic gonadotropin-treated immature rat ovary.
General properties of glycoprotein sialyl- and galactosyltransferases in control and hCG-primed immature rat ovary were studied by using asialo and agalacto derivatives of fetuin, alpha 1-acid glycoprotein, and purified O-glycosidically linked fetuin glycopeptide as exogenous substrates. Incorporation of the labeled sugars into the derivatives was determined by electrophoresis and precipitation with phosphotugnstic acid and with a rabbit anti-fetuin gamma-globulin fraction. Both enzyme activities were associated with partiulcate fractions, were enhanced by 0.3% Triton X-100, had pH optima between 6.3-6.6, and exhibited apparent Km values of 0.04-0.08 mM for the sugar nucleotides and 0.3-0.6 mM for the asialo- and asialoagalactofetuin derivatives. The galactosyltransferase required exogenous Mn+2 for activity. The specific activities of galactosyltransferase were similar in the control and hCG-primed ovaries, while the specific activity of sialytransferase in the hCG-primed ovaries was consistently twice that in the control.
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D005260:Female; D005700:Galactosyltransferases / Q000378:metabolism*; D007700:Kinetics; D010053:Ovary / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D012741:Sexual Maturation; D012799:Sialyltransferases / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism*; D000509:alpha-Fetoproteins / Q000096:biosynthesis
D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D014166:Transferases; D005700:Galactosyltransferases; D012799:Sialyltransferases