saccharopine脱氢酶在酿酒酵母的整体动力学机制。

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徐H、西啊,库克PF

saccharopine脱氢酶在酿酒酵母的整体动力学机制。

生物化学。2006年10月3;45 (39):12156 - 66。

PubMed ID

17002315 (在PubMed

]

文摘

动力学数据测量了histidine-tagged saccharopine脱氢酶从酿酒酵母,表明命令添加烟酰胺腺嘌呤二核苷酸(NAD)其次是saccharopine生理反应的方向。在相反的方向,还原型烟酰胺腺嘌呤二核苷酸(NADH)增加了酶首先,虽然没有偏爱的绑定alpha-ketoglutarate (alpha-Kg)和赖氨酸。saccharopine的方向形成,数据也表明,在高浓度时,赖氨酸自由酶抑制反应的绑定。此外,竞争力由alpha-Kg和双底物抑制抑制NAD和alpha-Kg建议流产的存在E: NAD: alpha-Kg复杂。产物抑制由saccharopine竞争力和NADH,暗示一个实际反应的不可逆性与整体K在pH值7.0协议(eq)。Saccharopine非竞争性与赖氨酸或alpha-Kg,表明存在两个E: NADH: Saccharopine和E: NAD: Saccharopine复合物。NAD和NADH具有竞争力,非竞争性和赖氨酸和alpha-Kg,表明二核苷酸的结合与自由酶。终端抑制研究也符合随机alpha-Kg和赖氨酸。亮氨酸和oxalylglycine作为赖氨酸和alpha-Kg终端类似物,分别对alpha-Kg竞争力对NADH和非竞争性和赖氨酸,分别。草酰乙酸盐(OAA)、丙酮酸和戊二酸的行为作为赖氨酸的终端类似物,这表明lysine-binding网站具有较高的亲和力比alpha-Kg网站或酮酸类似物二元羧酸酸酶有多个绑定模式。 In addition, OAA and glutarate also bind to free enzyme as does lysine at high concentrations. Glutarate gives S-parabolic noncompetitive inhibition versus NADH, indicating the formation of a E:(glutarate)2 complex as a result of occupying both the lysine- and alpha-Kg-binding sites. Pyruvate, a slow alternative keto acid substrate, exhibits competitive inhibition versus both lysine and alpha-Kg, suggesting the combination to the E:NADH:alpha-Kg and E:NADH:lysine enzyme forms. The equilibrium constant for the reaction has been measured at pH 7.0 as 3.9 x 10(-7) M by monitoring the change in NADH upon the addition of the enzyme. The Haldane relationship is in very good agreement with the directly measured value.

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药物靶点

药物	目标	类	生物	药理作用	行动
NADH	Alpha-aminoadipic semialdehyde合酶、线粒体	蛋白质	人类	未知的	不可用	细节