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Nat Struct Biol. 2001 Aug;8(8):679-83.

Structural insights into the hydrolysis of cellular nitric oxide synthase inhibitors by dimethylarginine dimethylaminohydrolase.

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School of Crystallography, Birkbeck, Malet Street, London WC1E 7HX, UK.

Erratum in

  • Nat Struct Biol 2001 Sep;8(9):818.


Nitric oxide synthase is inhibited by asymmetric NG-methylated derivatives of arginine whose cellular levels are controlled in part by dimethylarginine dimethylaminohydrolase (DDAH, EC Levels of asymmetric NG,NG-dimethylarginine (ADMA) are known to correlate with certain disease states. Here, the first structure of a DDAH shows an unexpected similarity to arginine:glycine amidinotransferase (EC and arginine deiminase (EC, thus defining a superfamily of arginine-modifying enzymes. The identification of a Cys-His-Glu catalytic triad and the structures of a Cys to Ser point mutant bound to both substrate and product suggest a reaction mechanism. Comparison of the ADMA-DDAH and arginine-amidinotransferase complexes reveals a dramatic rotation of the substrate that effectively maintains the orientation of the scissile bond of the substrate with respect to the catalytic residues. The DDAH structure will form a basis for the rational design of selective inhibitors, which are of potential use in modulating NO synthase activity in pathological settings.

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