Enzymatic synthesis of N,N-dimethyl-sphingosine: demonstration of the sphingosine: N-methyltransferase in mouse brain.

Based on our recent finding that N,N-dimethyl-D-erythro-sphingenine strongly inhibits protein kinase C (PK-C) whereas D-erythro-sphingenine produces only weak inhibition, we have studied the presence of N-methyltransferase responsible for conversion of sphingosine to its N,N-dimethyl derivative. The enzyme activity was detected in crude mouse brain tissue homogenate but was hardly detectable in liver homogenate, in which N-methylation of phosphatidylethanolamine (PE) is predominant.