Biosynthesis in vitro of sialyl(alpha 2-3)neolactotetraosylceramide by a sialyltransferase from embryonic chicken brain

J Biol Chem. 1982 Nov 10;257(21):12765-9.

Abstract

A sialyltransferase activity present in 7- to 12-day-old embryonic chicken brain catalyzes the transfer of sialic acid from CMP-sialic acid to the terminal galactose residue of [3H]nLcOse4Cer ([3H]Gal(beta 1-4).GlcNAc(beta 1-3)Gal(beta 1-4)Glc-Cer) to form NeuAc(alpha 2-3)-[3H]nLcOse4Cer (LM1 ganglioside). The product is sialidase-labile (96%), and the NeuAc group is linked to O-3 of the terminal galactose residue. The (alpha 2-3) linkage between sialic acid and the terminal galactose was determined on the basis of identification of 2,4,6-tri-O-methyl[3H]galactose obtained after hydrolysis of the permethylated enzymatic product. The CMP-sialic acid:nLcOse4Cer (alpha 2-3)sialyltransferase activity sediments (90%) at the junction of 1.2 M and 1.5 M on a discontinuous sucrose density gradient when still membrane bound (insoluble in 0.2% Triton X-100). The enzyme preparation also catalyzes the transfer of sialic acid from CMP-sialic acid to O-3 of GgOse4Cer (Gal(beta 1-3)GalNAc(beta 1-4)Gal(beta 1-4)Glc-Cer) to form NeuAc (alpha 2-3)GgOse4Cer (GM1b). Substrate inhibition studies indicate that these two reactions are probably catalyzed by the same enzyme.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Brain / embryology
  • Brain / enzymology*
  • Chick Embryo
  • Cytidine Monophosphate / pharmacology
  • Gangliosides / biosynthesis*
  • Kinetics
  • Sialyltransferases / isolation & purification
  • Sialyltransferases / metabolism*
  • Substrate Specificity
  • Transferases / metabolism*

Substances

  • Gangliosides
  • LM1 ganglioside
  • Transferases
  • Sialyltransferases
  • Cytidine Monophosphate