L-arginine binding to nitric-oxide synthase - The role of H-bonds to the nonreactive guanidinium nitrogens
L-arginine binding to nitric-oxide synthase - The role of H-bonds to the nonreactive guanidinium nitrogens
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DOI：
10.1074/jbc.274.36.25218
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发表时间：
1999-09-03
影响因子：
4.8
通讯作者：
Griffith, OW
中科院分区：
文献类型：
--
作者：
Babu, BR;Frey, C;Griffith, OW
一氧化氮合酶 (NOS) 催化 L-精氨酸氧化为一氧化氮和 L-瓜氨酸。由于一氧化氮的过量产生会导致神经、炎症和自身免疫性疾病中的组织损伤，因此 NOS 抑制剂的设计受到了广泛关注。迄今为止描述的大多数抑制剂都包含类似胍的结构基序，并与 L-精氨酸结合位点的胍区域相互作用。我们在这里报告了 L-精氨酸类似物的研究，其中一个或两个末端胍氮被功能性取代，这些功能性保留了 L-精氨酸的 -NH2、=NH 或 =NH2+ 基团可能的部分但不是全部分子相互作用。取代基团包括 -NH-烷基、-烷基、=O 和 =S。还检查了 L-刀豆氨酸（一种无法形成涉及 N-5-质子的氢键的类似物）的结合。根据我们的结果和之前的工作，我们推断出这些化合物在 L-精氨酸结合位点中的方向，并使用 IC50 或 K-i 值和光学差异光谱来定量它们相对于 L-精氨酸的亲和力。我们发现 L-精氨酸的非反应性胍氮结合在一个口袋中，该口袋相对不能容忍所结合基团的大小或氢键特性的变化。然而，涉及的个别氢键弱于预期（
Nitric-oxide synthase (NOS) catalyzes the oxidation of L-arginine to nitric oxide and L-citrulline. Because overproduction of nitric oxide causes tissue damage in neurological, inflammatory, and autoimmune disorders, design of NOS inhibitors has received much attention. Most inhibitors described to date include a guanidine-like structural motif and interact with the guanidinium region of the L-argnine-binding site. We report here studies with L-arginine analogs having one or both terminal guanidinium nitrogens replaced by functionalities that preserve some, but not all, of the molecular interactions possible for the -NH2, =NH, or =NH2+ groups of L-arginine, Replacement groups include -NH-alkyl, -alkyl, =O, and =S, Binding of L-canavanine, an analog unable to form hydrogen bonds involving a N-5-proton, was also examined. From our results and previous work, we infer the orientation of these compounds in the L-arginine-binding site and use IC50 or K-i values and optical difference spectra to quantitate their affinity relative to L-arginine, We find that the non-reactive guanidinium nitrogen of L-arginine binds in a pocket that is relatively intolerant of changes in the size or hydrogen bonding properties of the group bound. The individual H-bonds involved are, however, weaker than expected (