Department of Pharmaceutical Sciences, University of New Mexico, Albuquerque, NM 87131, USA.
FEBS Lett. 2011 Aug 19;585(16):2622-6. doi: 10.1016/j.febslet.2011.07.022. Epub 2011 Jul 26.
The FMN-heme intraprotein electron transfer (IET) kinetics in a human inducible NOS (iNOS) oxygenase/FMN construct were determined by laser flash photolysis as a function of solution viscosity (1.0-3.0 cP). In the presence of ethylene glycol or sucrose, an appreciable decrease in the IET rate constant value was observed with an increase in the solution viscosity. The IET rate constant is inversely proportional to the viscosity for both viscosogens. This demonstrates that viscosity, and not other properties of the added viscosogens, causes the dependence of IET rates on the solvent concentration. The IET kinetics results indicate that the FMN-heme IET in iNOS is gated by a large conformational change of the FMN domain. The kinetics and NOS flavin fluorescence results together indicate that the docked FMN/heme state is populated transiently.
人诱导型一氧化氮合酶（iNOS）氧合酶/FMN 结构中 FMN-血红素蛋白内电子转移（IET）动力学通过激光闪光光解法测定，作为溶液粘度（1.0-3.0 cP）的函数。在乙二醇或蔗糖的存在下，随着溶液粘度的增加，IET 速率常数值明显降低。对于两种增粘剂，IET 速率常数与粘度成反比。这表明，是粘度而不是添加增粘剂的其他性质导致 IET 速率对溶剂浓度的依赖性。IET 动力学结果表明，iNOS 中的 FMN-血红素 IET 受到 FMN 结构域的大构象变化的控制。动力学和 NOS 黄素荧光结果表明，对接的 FMN/血红素状态是短暂存在的。
