Effects of arginine derivatives on soluble guanylate cyclase from neuroblastoma N1E 115 cells

Abstract

The effects of l-arginine (Arg) derivatives on soluble guanylate cyclase from neuroblastoma N1E 115 cells were examined. The Arg derivatives were modified at the -NH 2, -COOH, Cα-proton or guanidino group of Arg. Among the synthesized derivatives, eight compounds, i.e. the 5-(dimethylamino)-1-naphthalenesulfonyl (DNS) ones, especially N-cyclohexyl-2-( N-DNSamino)-5-guanidino-2-methylvaleramide and 1-[2-( N-DNSamino)-2-(2-imino-1,2,3,4,5,6-hexahydropyrimidin-4-yl)acetyl]-piperidine, were found to inhibit the activity of crude guanylate cyclase in the 105,000 g supernatant fraction of the cell homogenate. The enzyme, partially purified by a column of Chelex 100 Na + was also inhibited by these eight compounds. The mode of the inhibition was competitive. The K i values were in the range of 2–8 μM for the enzyme in the 105,000g supernatant fraction and 3–16 μM for the partially purified enzyme, in the presence of Mg 2+ as a metal cofactor. In contrast, a new derivative, methyl 2-amino-5-guanidinovalerate (M Arg ME), as well as the Arg methyl ester (Arg ME) and Arg, were found to enhance the activity of the partially purified guanylate cyclase; K A values of M Arg ME, Arg ME and Arg were approximately 9, 4 and 3 μM respectively. From these results, the free guanidino group including 2-imino-1,2,3,4,5,6-hexahydropyrimidin-4-yl or 2-imino-1,2,3,4,5,6-hexahydropyrimidin-5-yl and modification of the -NH 2 residue with a hydrophobic group such as DNS seemed to be essential for inhibition of the guanylate cyclase; however, the guanidino and -NH 2 residue of Arg should be free for activation by these Arg derivatives.