Hydrolyzes N(G),N(G)-dimethyl-L-arginine (ADMA) and N(G)-monomethyl-L-arginine (MMA) which act as inhibitors of NOS. Has therefore a role in the regulation of nitric oxide generation. H2O + N(omega),N(omega)-dimethyl-L-arginine = dimethylamine + L-citrulline Copurifies with a tightly bound zinc ion. Activated by release of zinc. His and other agents that promote the release of bound zinc ions activate the enzyme (in vitro). Inhibited by S-nitrosylation. Zinc protects the protein against S-nitrosylation. Optimum pH is 7.8. Monomer. Widely distributed, highest concentrations found in brain, brain cortex and kidney (at protein level). Belongs to the DDAH family. Was originally thought to be a heme protein, but this was later shown to be an artifact.