title: Sialyltransferase of bovine serum: age- and hormone-related changes.
abstract: Sialyltransferase activity of bovine serum with the acceptor asialofetuin exhibits a pH optimum at 6.0-6.5, no divalent cation dependence, and a Km for CMP-sialic acid of 0.05 mM. Although a 2-fold increase in sialyltransferase activity with the acceptor asialofetuin is observed in serum samples from 2-day-old vs 20-day-old calves, the relative activity towards other glycoprotein acceptors is not different between the groups. With the acceptor lactose, the major product (greater than 95%) for all samples is 3'-sialyllactose, suggesting that the elevated levels of sialyltransferase in 2-day-old calves are due to Gal-R (alpha 2-3) sialyltransferase.
mesh_terms: D000375:Aging; D000818:Animals; D002413:Cations, Divalent; D002417:Cattle; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D012799:Sialyltransferases / Q000097:blood*; D014166:Transferases / Q000097:blood*
chemical_list: D002413:Cations, Divalent; D011374:Progesterone; D014166:Transferases; D012799:Sialyltransferases