Roche Camille J, Dantsker David, Samuni Uri, Friedman Joel M
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Biol Chem. 2006 Dec 1;281(48):36874-82. doi: 10.1074/jbc.M603914200. Epub 2006 Sep 19.
Nitrite reductase activity of deoxyhemoglobin (HbA) in the red blood cell has been proposed as a non-nitric-oxide synthase source of deliverable nitric oxide (NO) within the vasculature. An essential element in this scheme is the dependence of this reaction on the quaternary/tertiary structure of HbA. In the present work sol-gel encapsulation is used to trap and stabilize deoxy-HbA in either the T or R quaternary state, thus allowing for the clear-cut monitoring of nitrite reductase activity as a function of quaternary state with and without effectors. The results indicate that reaction is not only R-T-dependent but also heterotropic effector-dependent within a given quaternary state. The use of the maximum entropy method to analyze carbon monoxide (CO) recombination kinetics from fully and partially liganded sol-gel-encapsulated T-state species provides a framework for understanding effector modulation of T-state reactivity by influencing the distribution of high and low reactivity T-state conformations.
红细胞中脱氧血红蛋白（HbA）的亚硝酸还原酶活性被认为是脉管系统内可递送一氧化氮（NO）的非一氧化氮合酶来源。该机制中的一个关键要素是该反应对HbA四级/三级结构的依赖性。在本研究中，采用溶胶 - 凝胶包封法将脱氧 - HbA捕获并稳定在T或R四级状态，从而能够明确监测亚硝酸还原酶活性作为四级状态的函数，有无效应物均可。结果表明，该反应不仅依赖于R - T，而且在给定的四级状态下还依赖于异源效应物。使用最大熵方法分析完全和部分配体的溶胶 - 凝胶包封T态物种中的一氧化碳（CO）重组动力学，为理解效应物通过影响高反应性和低反应性T态构象的分布对T态反应性的调节提供了一个框架。
