Watmough N J, Cheesman M R, Gennis R B, Greenwood C, Thomson A J
Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, UK.
FEBS Lett. 1993 Mar 15;319(1-2):151-4. doi: 10.1016/0014-5793(93)80056-z.
Oxidised, formate-bound and fluoride-bound forms of E. coli cytochrome bo give rise to an electronic absorption band near 630 nm, diagnostic of high-spin ferric haem o, whose position is sensitive to the nature of the bound anion. In all three forms, haem o remains spin-coupled to Cu(B)(II), resulting in distinct broad X-band EPR signals. Those of formate-bound cytochrome bo are similar to the signals seen in slow cytochrome aa3 but cannot be induced by incubation at acid pH suggesting that the endogenous carboxylate believed to be important in slow cytochrome aa3 is not present in cytochrome bo. The oxidised form gives rise to novel EPR signals at g = 3.74 and g = 3.08 which have not been detected in cytochrome aa3 and may arise from a weak magnetic coupling between high-spin haem o, S = 5/2, and Cu(B)(II), S = 1/2.
大肠杆菌细胞色素bo的氧化态、甲酸结合态和氟化物结合态在630nm附近产生一个电子吸收带，这是高自旋铁血红素o的诊断特征，其位置对结合阴离子的性质敏感。在所有三种形式中，血红素o仍与铜（B）（II）自旋耦合，产生明显的宽X波段电子顺磁共振信号。甲酸结合的细胞色素bo的信号与慢细胞色素aa3中的信号相似，但在酸性pH下孵育不能诱导产生，这表明在慢细胞色素aa3中被认为重要的内源性羧酸盐在细胞色素bo中不存在。氧化态在g = 3.74和g = 3.08处产生新的电子顺磁共振信号，这些信号在细胞色素aa3中未被检测到，可能源于高自旋血红素o（S = 5/2）和铜（B）（II）（S = 1/2）之间的弱磁耦合。
