Classical and Slow-Binding Inhibitors of Human Type II Arginase
Arginases catalyze the hydrolysis of l-arginine to yield l-ornithine and urea. Recent studies indicate that arginases, both the type I and type II isozymes, participate in the regulation of nitric oxide production by modulating the availability of arginine for nitric oxide synthase. Due to the recip...
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Published in | Biochemistry (Easton) Vol. 40; no. 31; pp. 9356 - 9362 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
07.08.2001
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Subjects | |
Online Access | Get full text |
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Summary: | Arginases catalyze the hydrolysis of l-arginine to yield l-ornithine and urea. Recent studies indicate that arginases, both the type I and type II isozymes, participate in the regulation of nitric oxide production by modulating the availability of arginine for nitric oxide synthase. Due to the reciprocal regulation between arginase and nitric oxide synthase, arginase inhibitors have therapeutic potential in treating nitric oxide-dependent smooth muscle disorders, such as erectile dysfunction. We demonstrate the competitive inhibition of the mitochondrial human type II arginase by N ω-hydroxy-l-arginine, the intermediate in the reaction catalyzed by nitric oxide synthase, and its analogue N ω-hydroxy-nor-l-arginine, with K i values of 1.6 μM and 51 nM at pH 7.5, respectively. We also demonstrate the inhibition of human type II arginase by the boronic acid-based transition-state analogues 2(S)-amino-6-boronohexanoic acid (ABH) and S-(2-boronoethyl)-l-cysteine (BEC), which are known inhibitors of type I arginase. At pH 7.5, both ABH and BEC are classical, competitive inhibitors of human type II arginase with K i values of 0.25 and 0.31 μM, respectively. However, at pH 9.5, ABH and BEC are slow-binding inhibitors of the enzyme with K i values of 8.5 and 30 nM, respectively. The findings presented here indicate that the design of arginine analogues with uncharged, tetrahedral functional groups will lead to the development of more potent inhibitors of arginases at physiological pH. |
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Bibliography: | istex:3171E958D62912D9F05118D151D80C64E74DF850 ark:/67375/TPS-32R5LZLS-5 This work was supported by NIH Grant DK44841. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi010783g |