Helms Christine, Kim-Shapiro Daniel B
Department of Physics and Translational Science Center, Wake Forest University, Winston-Salem, NC 27109, USA.
Department of Physics and Translational Science Center, Wake Forest University, Winston-Salem, NC 27109, USA.
Free Radic Biol Med. 2013 Aug;61:464-72. doi: 10.1016/j.freeradbiomed.2013.04.028. Epub 2013 Apr 26.
The rate that hemoglobin reacts with nitric oxide (NO) is limited by how fast NO can diffuse into the heme pocket. The reaction is as fast as any ligand/protein reaction can be and the result, when hemoglobin is in its oxygenated form, is formation of nitrate in what is known as the dioxygenation reaction. As nitrate, at the concentrations made through the dioxygenation reaction, is biologically inert, the only role hemoglobin was once thought to play in NO signaling was to inhibit it. However, there are now several mechanisms that have been discovered by which hemoglobin may preserve, control, and even create NO activity. These mechanisms involve compartmentalization of reacting species and conversion of NO from or into other species such as nitrosothiols or nitrite which could transport NO activity. Despite the tremendous amount of work devoted to this field, major questions concerning precise mechanisms of NO activity preservation as well as if and how Hb creates NO activity remain unanswered.
血红蛋白与一氧化氮（NO）反应的速率受限于NO扩散进入血红素口袋的速度。该反应的速度与任何配体/蛋白质反应一样快，当血红蛋白处于氧合形式时，反应结果是在所谓的双加氧反应中形成硝酸盐。由于通过双加氧反应产生的浓度下的硝酸盐是生物惰性的，血红蛋白曾被认为在NO信号传导中唯一的作用是抑制它。然而，现在已经发现了几种机制，通过这些机制血红蛋白可能保存、控制甚至产生NO活性。这些机制涉及反应物种的区室化以及NO与其他物种（如亚硝基硫醇或亚硝酸盐）之间的转化，这些物种可以传递NO活性。尽管在该领域投入了大量工作，但关于NO活性保存的精确机制以及血红蛋白是否以及如何产生NO活性的主要问题仍未得到解答。
