Bradić Z, Harrington P C, Wilkins R G, Yoneda G
Biochemistry. 1980 Sep 2;19(18):4149-55. doi: 10.1021/bi00559a003.
The oxidation of deoxy- and oxyhemerythrin to methemerythrin by Fe(CN)6(3-) has been examined. The first step produces (semi-met)O, a half-oxidized form of hemerythrin which has different spectral and kinetic properties from (semi-met)R which is produced by one-electron reduction of methemerythrin. Further oxidation of (semi-met)O to methemerythrin usually occurs only indirectly via disproportionation of (semi-met)O to met and deoxy forms within the octameric framework. Oxidation of (semi-met)R by Fe(CN)6(3-) is a direct second-order reaction. (Semi-met)O is reduced rapidly by dithionite to deoxy, whereas that of (semi-met)R is a slow biphasic process. The oxidation of oxyhemerythrin occurs via the deoxy species, little, if any, reactivity being attributable to the oxy form. The oxidation of the azide adduct of (semi-met)R is biphasic, in which in step one N3(-) is removed during the oxidation to methemerythrin, which in the second step recombines with N3(-). Rate parameters for all these processes at pH 8.2 and 6.3 for protein from Phascolopsis gouldii and Themiste zostericola have been obtained. The implications of these findings to hemerythrin chemistry are discussed.
研究了Fe(CN)6(3-)将脱氧和氧合蚯蚓血红蛋白氧化为高铁蚯蚓血红蛋白的过程。第一步生成(semi-met)O，这是蚯蚓血红蛋白的一种半氧化形式，其光谱和动力学性质与通过高铁蚯蚓血红蛋白单电子还原产生的(semi-met)R不同。(semi-met)O进一步氧化为高铁蚯蚓血红蛋白通常仅通过八聚体框架内(semi-met)O歧化为高铁和脱氧形式间接发生。Fe(CN)6(3-)氧化(semi-met)R是一个直接的二级反应。(semi-met)O被连二亚硫酸盐迅速还原为脱氧形式，而(semi-met)R的还原是一个缓慢的双相过程。氧合蚯蚓血红蛋白的氧化通过脱氧物种发生，氧合形式几乎没有反应活性。(semi-met)R的叠氮化物加合物的氧化是双相的，第一步在氧化为高铁蚯蚓血红蛋白的过程中N3(-)被去除，第二步N3(-)重新结合。已获得在pH 8.2和6.3条件下，来自古氏管体虫和带状拟帚毛虫的蛋白质的所有这些过程的速率参数。讨论了这些发现对蚯蚓血红蛋白化学的意义。
