Dimethylarginine Dimethylaminohydrolase 1 (DDAH1)

DDAH is an enzyme found in all mammalian cells. Two isoforms exist, DDAH I and DDAH II, with some differences in tissue distribution of the two isoforms). The enzyme degrades methylarginines, specifically asymmetric dimethylarginine (ADMA) and NG-monomethyl-L-arginine (MMA). The methylarginines ADMA and MMA inhibit the production of nitric oxide synthase. Accordingly, DDAH is important in removing methylarginines, generated by protein degradation, from accumulating and inhibiting the generation of nitric oxide.The DDAHI cDNA encodes a 285-amino acid protein with 62% identity with human DDAHII and 95% identity with rat DdahI proteins. Northern blot analysis identified a 4.4-kb DDAHI mRNA present at highest levels in brain, kidney, pancreas, and liver.