Identification of the 4-amino analogue of tetrahydrobiopterin as a dihydropteridine reductase inhibitor and a potent pteridine antagonist of rat neuronal nitric oxide synthase.
Identification of the 4-amino analogue of tetrahydrobiopterin as a dihydropteridine reductase inhibitor and a potent pteridine antagonist of rat neuronal nitric oxide synthase.
复制标题
鉴定四氢生物蝶呤的 4-氨基类似物作为二氢蝶啶还原酶抑制剂和大鼠神经元一氧化氮合酶的有效蝶啶拮抗剂。
作者：
E. Werner;E. Pitters;K. Schmidt;H. Wachter;G. Werner;B. Mayer
通过与6 R-[3 ′-3H]-5，6，7，8-四氢-L-赤型生物蝶呤（6 R-[3 ′-3H] H4生物蝶呤）竞争，测定具有6-二羟丙基和三羟丙基侧链的四氢蝶啶与重组大鼠神经元一氧化氮（NO）合酶（EC 1.14.13.39）的结合。尽管除了一种衍生物外，所有衍生物仅表现出较差的亲和力（Ki 50 μ M），但6 R-H4生物蝶呤的4-氨基类似物是6 R-H4生物蝶呤结合的有效拮抗剂（Ki 13.2 nM）。6 R-H4生物蝶呤的4-氨基类似物以1 μ M的IC 50抑制天然辅因子6 R-H4生物蝶呤对NO合酶的刺激，而不影响在不添加6 R-H4生物蝶呤的情况下观察到的基础活性。因为6 R-H4生物蝶呤的4-氨基类似物也抑制二氢蝶啶还原酶（EC 1.6.99.7; IC 50 20 μ M），我们的结果支持H4生物蝶呤的氧化还原循环可能是NO合酶反应所需的假设。
The binding of tetrahydropteridines with 6-di- and trihydroxypropyl side chains to recombinant rat neuronal nitric oxide (NO) synthase (EC 1.14.13.39) was determined by competition with 6R-[3'-3H]-5,6,7,8-tetrahydro-L-erythro-biopterin (6R-[3'-3H]H4biopterin). Although all but one of the derivatives exhibited only poor affinities (Ki 50 microM), the 4-amino analogue of 6R-H4 biopterin was a potent antagonist of 6R-H4 biopterin binding (Ki 13.2 nM). The 4-amino analogue of 6R-H4 biopterin inhibited NO synthase stimulation by the natural cofactor 6R-H4 biopterin with an IC50 of 1 microM without affecting the basal activity observed in the absence of added 6R-H4 biopterin. Because the 4-amino analogue of 6R-H4biopterin also inhibited dihydropteridine reductase (EC 1.6.99.7; IC50 20 microM), our results support the hypothesis that redox cycling of H4 biopterin might be required for the NO synthase reaction.