Abstract
To date, sterylglucosides have been reported to be present in various fungi, plants, and animals. In bacteria, such as Helicobacter pylori, proton NMR spectral analysis of isolated 1-O-cholesteryl-β-d-glucopyranoside (GlcChol) demonstrated the presence of an α-glucosidic linkage. By contrast, in animals, no detailed structural analysis of GlcChol has been reported, in part because animal-derived samples contain a high abundance of glucosylceramides (GlcCers)/galactosylceramides, which exhibit highly similar chromatographic behavior to GlcChol. A key step in vertebrate GlcChol biosynthesis is the transglucosylation reaction catalyzed by glucocerebrosidase (GBA)1 or GBA2, utilizing GlcCer as a glucose donor. These steps are expected to produce a β-glucosidic linkage. Impaired GBA1 and GBA2 function is associated with neurological disorders, such as cerebellar ataxia, spastic paraplegia, and Parkinson's disease. Utilizing a novel three-step chromatographic procedure, we prepared highly enriched GlcChol from embryonic chicken brain, allowing complete structural confirmation of the β-glucosidic linkage by 1H-NMR analysis. Unexpectedly, during purification, two additional sterylglucoside fractions were isolated. NMR and GC/MS analyses confirmed that the plant-type sitosterylglucoside in vertebrate brain is present throughout embryonic development. The aglycon structure of the remaining sterylglucoside (GSX-2) remains elusive due to its low abundance. Together, our results uncovered unexpected aglycon heterogeneity of sterylglucosides in vertebrate brain.
Highlights
To date, sterylglucosides have been reported to be present in various fungi, plants, and animals
Our work described here is the first report to describe the complete structure of 1-O-cholesteryl- -d-glucopyranoside (GlcChol) and 1-O-sitosteryl- -d-glucopyranoside [(GlcSito), known as glucosyl- -d-sitosterol] derived from vertebrate brain and to demonstrate that sterylglucosides have a heterogeneous aglycon composition
After hydrolysis of the glycerophospholipid fraction, sterylglucosides were enriched by normal phase chromatography, utilizing a C:M gradient during elution, together with the large excess of GalCer known to be present in vertebrate brain
Summary
Sterylglucosides have been reported to be present in various fungi, plants, and animals In bacteria, such as Helicobacter pylori, proton NMR spectral analysis of isolated 1-O-cholesteryl- -d-glucopyranoside (GlcChol) demonstrated the presence of an -glucosidic linkage. This article is available online at http://www.jlr.org sterol glucosylation has been encountered in bacteria, fungi, plants, and animals [see review [1]], indicating its important role during the evolution of life. While bacteria, such as Helicobacter pylori, produce large amounts of 1-O-cholesteryl- -dglucopyranoside [2], animals such as chickens and snakes [3, 4] produce 1-O-cholesteryl- -d-glucopyranoside (GlcChol), known as glucosyl- -d-cholesterol
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