Inhibitors of brain nitric oxide synthase. Binding kinetics, metabolism, and enzyme inactivation.
Inhibitors of brain nitric oxide synthase. Binding kinetics, metabolism, and enzyme inactivation.
复制标题
脑一氧化氮合酶抑制剂。
DOI：
10.1016/s0021-9258(17)42080-1
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Bernd Mayer
中科院分区：
文献类型：
--
作者：
Peter Klatt;Kurt Schmidt;Friedrich Brunner;Bernd Mayer
Nitric oxide (NO) is synthesized from L-arginine by different NO synthase isozymes, which are inhibited by the substrate analogs NG-methyl- and NG-nitro-L-arginine. We studied binding of 3H-labeled NG-nitro-L-arginine to purified brain NO synthase and compared the data with results obtained in enzyme kinetic experiments. Binding data revealed a single binding site for NG-nitro-L-[3H]arginine (KD = 0.17 microM). Binding was competitively antagonized by L-arginine (KI = 2.9 microM). The half-time of dissociation was remarkably slow (9.4 min) and closely correlated with the time necessary for surmounting NO synthase inhibition by dilution. Although an apparently less potent inhibitor, NG-methyl-L-arginine exhibited the same affinity for brain NO synthase as the nitro derivative (KI = 0.17 microM), and in initial rate experiments, almost equal KI values were obtained for NG-methyl-L-arginine (0.61 microM) and NG-nitro-L-arginine (0.53 microM). However, after prolonged incubation periods, NG-nitro-L-arginine induced a rapid inactivation of the enzyme, whereas the methyl derivative turned out to be a substrate of NO synthase, which was slowly converted into stoichiometric amounts of NO and L-citrulline.
