Inhibition of L-Arginine Metabolizing Enzymes by L-Arginine-Derived Advanced Glycation End Products
Inhibition of L-Arginine Metabolizing Enzymes by L-Arginine-Derived Advanced Glycation End Products
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DOI：
10.3164/jcbn.09-104
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发表时间：
2010-03-01
影响因子：
2.4
通讯作者：
Ohshima, Hiroshi
中科院分区：
文献类型：
--
作者：
Lai, Ying-Ling;Aoyama, Sae;Ohshima, Hiroshi
N-欧米茄-羧甲基-精氨酸、N-欧米伽-羧乙基-精氨酸和N-delta-(5-hydro-5-methy1-4-imidazolon-2-yl)-ornithine(MG-H1)被鉴定为L-精氨酸衍生的晚期糖基化终末产物(AGEs)，由葡萄糖等还原糖与蛋白质中的氨基发生非酶反应而形成。这些AGEs在结构上类似于内源性一氧化氮合酶抑制剂，包括N-G-单甲基-L-精氨酸和不对称N-G-二甲基-L-精氨酸。这些一氧化氮合酶抑制物的血浆水平升高，从而影响体内一氧化氮的生成，与肾功能衰竭和动脉粥样硬化等血管并发症的发病机制有关。为此，我们研究了L精氨酸衍生的AGEs是否抑制了三种L精氨酸代谢酶的活性，包括三种不同亚型的一氧化氮合酶(内皮、神经元和诱导型一氧化氮合酶)、催化L-N甲基甲基丙酸和二甲基精氨酸二甲氨基水解酶的二甲基精氨酸二甲氨基水解酶以及调节细胞内L精氨酸生物利用度的精氨酸酶。我们发现AGEs对体外培养的内皮型一氧化氮合酶有微弱的抑制作用(CMA、CEA和MG-H1的IC50值分别为830、3870和1280 mU M)，对精氨酸酶也有潜在的内源性抑制作用(CMA和CML的IC50分别为1470和1060 mU M)，但对DDAH的抑制作用较差。这些结果表明，L-精氨酸和L-赖氨酸衍生的AGE似乎不会直接损害NO的生物合成。
N-omega-Carboxymethyl-arginine (CMA), N-omega-carboxyethyl-arginine (CEA) and N-delta-(5-hydro-5-methy1-4-imidazolon-2-yl)-ornithine (MG-H1) have been identified as L-arginine-derived advanced glycation end products (AGEs) formed by non-enzymatic reactions between reducing sugars such as glucose and amino groups in proteins. These AGEs are structurally analogous to endogenous inhibitors of nitric oxide synthases (NOS) including N-G-monomethyl-L-arginine (L-NMMA) and asymmetric N-G,N-G-dimethyl-L-arginine (ADMA). Increased plasma levels of these NOS inhibitors, and thus impaired generation of NO in vivo has been associated with the pathogenesis of vascular complications such as kidney failure and atherosclerosis. For these reasons we examined whether L-arginine-derived AGEs inhibit the activities of three L-arginine metabolizing enzymes including three isoforms of NOS (endothelium, neuronal and inducible NOS), dimethylarginine dimethylaminohydrolase (DDAH) that catalyzes the hydrolytic degradation of L-NMMA and ADMA to L-citrulline, and arginase that modulates intracellular L-arginine bioavailability. We found that AGEs inhibited the in vitro activities of endothelium type NOS weakly (IC50 values of CMA, CEA and MG-H1 were 830, 3870 and 1280 mu M, respectively) and were also potential endogenous inhibitors for arginase (IC50 values of CMA and CML were 1470 and 1060 mu M), but were poor inhibitors for DDAH. These results suggest that the tested L-arginine- and L-lysine-derived AGEs appear not to impair NO biosynthesis directly.