In vitro biosynthesis of sialosylgalactosylceramide (G7) by mouse brain microsomes

Robert K Yu, S. H. Lee

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

A sialyltransferase activity which catalyzes the synthesis of sialosylgalactosylceramide (G7) from added galactocerebroside and CMP N acetylneuraminic acid has been demonstrated in mouse brain microsomes. The enzyme reactions shows a pH optimum of 6.3 and requires detergents. Both Mn2+ and Ca2+ inhibited the reaction, whereas Mg2+ had no effect. The apparent Km for galactocerebroside leading to G7 was estimated to be 8.7 x 10-4 M. The same microsomal preparation also synthesized hematoside when ceramide lactoside was the glycolipid acceptor. The apparent Km for ceramide lactoside was about 1/10th that for galactocerebroside. When the preparations were partially inactivated by heat the synthesis of G7 and of hematoside was reduced at approximately the same rate. Liver appeared to have the highest activity for G7 synthesis (as well as of hematoside), followed by brain. The synthesis of G7 by mouse brain microsomes in vitro demonstrates a new pathway for brain ganglioside synthesis.

Original languageEnglish (US)
Pages (from-to)198-203
Number of pages6
JournalJournal of Biological Chemistry
Volume251
Issue number1
StatePublished - Dec 1 1976
Externally publishedYes

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Biosynthesis
G(M3) Ganglioside
Microsomes
Brain
Sialyltransferases
Cytidine Monophosphate
Gangliosides
Glycolipids
N-Acetylneuraminic Acid
Detergents
Hot Temperature
Liver
In Vitro Techniques
Enzymes
galactocerebroside
CDw17 antigen

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

In vitro biosynthesis of sialosylgalactosylceramide (G7) by mouse brain microsomes. / Yu, Robert K; Lee, S. H.

In: Journal of Biological Chemistry, Vol. 251, No. 1, 01.12.1976, p. 198-203.

Research output: Contribution to journalArticle

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AB - A sialyltransferase activity which catalyzes the synthesis of sialosylgalactosylceramide (G7) from added galactocerebroside and CMP N acetylneuraminic acid has been demonstrated in mouse brain microsomes. The enzyme reactions shows a pH optimum of 6.3 and requires detergents. Both Mn2+ and Ca2+ inhibited the reaction, whereas Mg2+ had no effect. The apparent Km for galactocerebroside leading to G7 was estimated to be 8.7 x 10-4 M. The same microsomal preparation also synthesized hematoside when ceramide lactoside was the glycolipid acceptor. The apparent Km for ceramide lactoside was about 1/10th that for galactocerebroside. When the preparations were partially inactivated by heat the synthesis of G7 and of hematoside was reduced at approximately the same rate. Liver appeared to have the highest activity for G7 synthesis (as well as of hematoside), followed by brain. The synthesis of G7 by mouse brain microsomes in vitro demonstrates a new pathway for brain ganglioside synthesis.

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