ISOLATION AND IDENTIFICATION OF METHYLARGININES FROM BOVINE BRAIN

Methylarginines in free form were identified in bovine brain. Three compounds were isolated from the basic aliphatic amino acid fraction of bovine brain with several ion-exchange chromatographies. They showed the same R(f) values in paper and thin-layer chromatographies as those of authentic N(G)-monomethylarginine, N(G),N(G)-dimethylarginine, and N(G),N'(G)-dimethylarginine. The migration distance of the isolated compounds in high-voltage paper electrophoresis and the retention times in ion-exchange HPLC were also identical to those of the above authentic methylarginines. We concluded that these three compounds are the methyl derivatives of arginine described above. The amount of these three compounds isolated from 1,090 g of bovine brain was 0.3-mu-mol of N(G)-monomethylarginine, 0.1-mu-mol of N(G),N(G)-dimethylarginine, and 0.5-mu-mol of N(G),N'(G)-dimethylarginine. The occurrence of these free methylarginines may have an important role in regulating the signal transduction through the nitric oxide system.