A novel synthesis of ceramide from lignoceric acid and sphingosine by rat brain preparation; the amide formation requires a pyridine nucleotide.

The conversion of free lignoceric acid and sphingosine to lignoceroyl sphingosine (ceramide) by rat brain particulate fraction and two cytosolic factors, one heat-stable and the other heat-labile, requires pyridine nucleotide. This enzymatic reaction is apparently different from two previously published enzymic reactions, microsomal sphingosine:acyl CoA acyltransferase and the reverse reaction of lysosomal ceramidase. The reaction is strongly inhibited by common respiratory chain inhibitors, KCN, Antimycin A and sodium azide, this indicates the involvement of an electron-transfer system. From these observations it appears that the brain ceramide synthesis described above is catalyzed by an enzyme system which involves a mechanism for amide formation which has not been previously characterized.