Chemical characterization of penta-, hexa-, hepta-, octa-, and nonaglycosylceramides of rat small intestine having a globoside-like terminus.

• A novel series of glycosphingolipids has been isolated from the nonepithelial part of rat small intestine. A mixed fraction containing 3 major components corresponding to glycolipids with 5, 6, and 7 sugars and 2 minor components with 8 and 9 sugars was characterized. The structure of the major components was deduced by mass spectrometry and proton NMR spectroscopy of nondegraded permethylated and permethylated-reduced (LiAlH4) derivatives and gas-liquid chromatography of degradation products of native, permethylated, and permethylated-reduced glycolipids. The structures of the penta-, hexa-, and hepta-glycosylceramides were found to be GalNAcp beta 1 leads to (3Galp alpha 1 leads to)2-44Galp beta 1 leads to 4Glcp beta 1 leads to 1Cer. By analogy reasoning, supported by mass spectrometry, the octa- and nonaglycosylceramides were concluded to have 1 and 2 additional internal leads to 3Galp alpha 1 leads to 3 structures, respectively. A pentaglycosylceramide fraction from another rat strain was also isolated. The NMR spectra were in agreement with 2 isomeric structures of which 1 had the internal alpha 1 leads to 4 linkage replaced by an alpha 1 leads to 3 linkage. The fatty acids of all components were nonhydroxy 16:0 to 24:0 acids with the 18:0 homologue as dominating species. The major base was sphingosine and possibly monohydroxy 18:1 base in the larger glycolipids. This is a novel series of structures with a terminal saccharide identical with isoglobotetraoxylceramide (cytolipin R). The glycosyltransferase for the terminal GalNAc beta 1 leads to 3 of cytolipin R may possibly be identical with the enzyme adding the terminal sugar of this novel series. This is supported by the presence in the same tissue of probable precursor glycolipids with 4 to 8 hexoses.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

Keyword

Animals

Carbohydrate Conformation

Carbohydrate Sequence

Globosides

analysis

Glycosphingolipids

analysis

Intestine

Small

analysis

Mass Spectrometry

Models

Molecular

Rats

Rats

Inbred Strains

Publication and Content Type

ref (subject category)

art (subject category)