SYNTHESIS OF CEREBROSIDE BY BRAIN FROM URIDINE DIPHOSPHATE GALACTOSE AND CERAMIDE CONTAINING HYDROXY FATTY ACID

A crude microsomal fraction from the brains of young mice catalyzes the formation of galactosylceramide containing hydroxy fatty acids from 2-hydroxy fatty acid ceramide and uridine diphosphate galactose. The 2-hydroxy fatty acid ceramide is most effective as a substrate when it is spread over the large surface area offered by the diatomaceous earth, Celite, in the absence of detergent. The enzyme system exhibits high specificity: ceramide containing nonhydroxy fatty acids will notstimulate galactose incorporation and only uridine diphosphate galactose or a uridine diphosphate galactose generating system acts as a sugar donor. The product of the incubation mixture has been characterized as 2-hydroxy fatty acid galactosylceramide by a variety of chromatographic and chemicalprocedures. Some other properties of the system were investigated. The results are discussed and related to our present knowledge of sphingolipid metabolism. © 1969, American Chemical Society. All rights reserved.