Dimethylarginine dimethylaminohydrolase

ADMA is degraded by the enzyme dimethylarginine dimethylaminohydrolase (DDAH), which hydrolyzes ADMA to L-citrulline and dimethylamine [70,83]. Two isoforms of this enzyme have been characterized and cloned to date. DDAH I predominates in tissues that express neuronal NOS and DDAH II predominates in tissues expressing endothelial NOS [70,84]. Activity of DDAH has been shown to be decreased by oxidized low density lipoprotein (LDL) or tumor necrosis factor-a (TNF-a) in vitro yielding increased levels of ADMA. Plasma levels of ADMA were found elevated in hyperhomo-cysteinemia, hypercholesterolemia and in hypertensive patients on a high salt diet [70,72,73]. 

M. Kimoto, G. S. Whitley. H. Tsuji and T. Ogawa, Detection of NG.NG-Dimethylarginine Dimethylaminohydrolase in Human Tissues Using a Monoclonal NnUhoA v. Journal of Biochemistry 117(1995)237-238. 

J. M. Leiper, J. Santa-Maria. A. Chubb, R. J. MacAlIister, 1. G. Charles, G. S. Whitley and P. Vallance, Identification of Two Human Dimethylarginine Dimethylaminohydrolases with Distinct Tissue Distributions and Homology w ith Microbial. Arginine Deiminases. Biochemical Journal 343... 

Figure 9 Endogenously produced, asymmetrically N -methylated arginines (12,13) inhibit NO synthase, but 14 does not. Hydrolysis of asymmetrically methylated arginine residues by dimethylarginine dimethylaminohydrolase (DDAH) can relieve this inhibition and promote NO biosynthesis.

B) reaction associated with the accumulation of S-adenosylhomocysteine (SAH) due to persistent slowing of the hydrolysis of SAH and (C) reactions due to the inhibition of dimethylarginine dimethylaminohydrolase (DDAH). 

Ogawa, T., M. Kimoto, and K. Sasaoka, 1989. Purification and properties of a new enzyme, Ng,Ng-dimethylarginine dimethylaminohydrolase, fiom rat-kidney. J. Biol. Chenr 264, 10205-10209. 

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