Enzymatic synthesis of neolactotetraosylceramide by the N-acetyllactosamine synthase of human serum

Eur J Biochem. 1982 Jul;125(2):323-9. doi: 10.1111/j.1432-1033.1982.tb06686.x.

Abstract

A high galactosyltransferase activity with lactotriaosylceramide as acceptor has been found in human serums. The reaction requires UDP-galactose, Mn2+, and Triton X-100. It has a pH optimum of 6.0 and a Km for lactotriaosylceramide of 0.66 mM. On the basis of methylation analysis and susceptibility towards beta-galactosidase the reaction product has been identified as neolactotetraosylceramide. Lactotetraosylceramide formation was not observed. Evidence is presented that the serum enzymic activity can be attributed to N-acetyllactosamine synthase (EC 2.4.1.90). The beta 1 leads to 4-galactosyltransferase activities with lactotriaosylceramide as acceptor have been determined in different human sera. The activity is independent of ABO, p and Rh blood-group status. The enzyme is within a normal range in serums of cancer patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Group Antigens
  • Chemical Phenomena
  • Chemistry
  • Globosides*
  • Glycoside Hydrolases / metabolism
  • Glycosphingolipids / biosynthesis*
  • Humans
  • Lactose Synthase / blood*
  • Lactosylceramides / biosynthesis*
  • N-Acetyllactosamine Synthase / blood*
  • Neoplasms / blood
  • Neoplasms / enzymology
  • Rabbits
  • Substrate Specificity

Substances

  • Blood Group Antigens
  • Globosides
  • Glycosphingolipids
  • Lactosylceramides
  • paragloboside
  • Lactose Synthase
  • N-Acetyllactosamine Synthase
  • Glycoside Hydrolases