Natural occurrence of ganglioside lactones. Isolation and characterization of GD1b inner ester from adult human brain.

L Riboni,S Sonnino,D Acquotti,A Malesci,R Ghidoni,H Egge,S Mingrino,G Tettamanti

doi:10.1016/s0021-9258(19)83940-6

Abstract

A new ganglioside containing an inner ester linkage was extracted from adult brain specimens, obtained at the time of surgery on 51-70-year-old subjects, purified, and analyzed. It contains glucose, galactose, N-acetylgalactosamine, an N-acetylneuraminic acid in the molar ratio 1:2:1:2, but, on ion-exchange chromatography, behaves as a monosialoganglioside. Structural analyses showed its basic neutral glycosphingolipid core to be ganglio-N-tetraose ceramide, carrying a disialosyl residue on the 3-position of internal galactose. Sialidase degradation and chemical analysis of the products obtained after alkaline treatments suggested one sialic acid residue to be involved in an ester linkage. Fast atom bombardment-mass spectrometry indicated the presence of an inner ester linkage between the carboxyl group of the external sialic acid residue and a hydroxyl group of the internal one. On these bases, the new ganglioside can be assumed to be a GD1b in lactonic form. This ganglioside is present only in trace amounts in the brain of infants, but its content increases with age, reaching a value of 3.5% of total sialic acid in 51-70-year-old subjects.

Highlights

From the Study Center for the Functional Biochemistry of Brain Lipids, Department of Medical Chemistry and Biochemistry, Medical School,University of Milano, 20133 Milano, Italy, the SInstitut fur Physwlogische Chemie, Uniuersitat Bonn, Bonn, Federal Republic of Germany, and the YDiuision of Neurosurgery, University Hospital, Padova, Italy
The two-dimensional TLC analysis of gangliosides from adult human cerebral cortex is reported in Fig. 1; the relative
Gangliosides are sialic acid-containing glycosphingolipids that reside in the plasma membranes of vertebrate cells [1]; their oligosaccharide chains, protruding from the cell surface, diagrammatic representation together with the codes recently introduced [7] are given

Summary

Introduction

Cated the presence of an inner ester linkage between In thispaper we produce definite evidence of the presence, the carboxyl group of the external sialic acid residue in nature, of a ganglioside in lactonic form; this ganglioside, and a hydroxyl grouopf the internal one. The possible esterification of the carboxyl group of a sialic acid with one of the hydroxyl groups present inthe ganglioside molecule, with the concomitant formation of a ganglioside lactone, was proposed by Kuhn and Muldner in 1964 [3] and

Results

Conclusion