The biosynthesis by brain microsomes of cerebrosides containing nonhydroxy fatty acids,

Abstract

Incubation of microsomes from mouse brain with UDP-gal, a long-chain base, and 14C-fatty acyl-CoA resulted in formation of NFA-cerebroside labeled in the fatty acid residue. The rate of synthesis was ten times that of the system lacking UDP-gal or long chain base. The incubation system also formed NFA-ceramide, at a much higher rate. Stearoyl- and lignoceroyl-CoA were much more effective in forming ceramide and cerebroside than palmitoyl- and oleoyl-CoA, a correlation which suggests that ceramide is an intermediate in cerebroside biosynthesis.When NFA-ceramide, together with a phospholipid mixture, was incubated with labeled UDP-gal, NFA-cerebroside was formed. Utilization of the exogenous ceramide was demonstrated by a number of Chromatographie procedures. Under the same conditions, but with labeled UDP-glc, the corresponding glucose-containing cerebroside was formed, at a somewhat higher rate.The organic synthesis of labeled lignoceric acid and lignoceroyl -sphingosine is described. Also described is a simplified method for large-scale preparation of purified -sphingosine. The labeled ceramide was utilized by the microsomes for the formation of galactosyl lignoceroyl sphingosine.Under a variety of conditions the microsomes failed to convert psychosine and labeled acyl-CoA to cerebroside.