Hirota S, Kishi M, Yamauchi O, Wang Y H, Huang Z X
Department of Chemistry, Research Center for Materials Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan.
Biochem Biophys Res Commun. 2001 Mar 23;282(1):351-5. doi: 10.1006/bbrc.2001.4544.
CO complex of cyt b(5) generated at acidic pH is investigated by absorption, resonance Raman (RR), and far UV CD measurements. The Soret maximum wavelength blue-shifted to 420 nm with other absorption bands observed around 540 and 570 nm for reduced cyt b(5) upon interaction with CO at acidic pH (pH 3.1-3.5). Under this condition, the iron-carbon stretching RR band was observed at 529 cm(-1) (520 cm(-1) for C(18)O), which indicated formation of a heme&bond;CO adduct with a histidine as an axial ligand. Heme dissociated from the reduced cyt b(5) protein at pH approximately 3.5, whereas its rate decreased under CO atmosphere compared with N(2) atmosphere, due to formation of a heme&bond;CO adduct with a histidine as an axial ligand.
通过吸收光谱、共振拉曼光谱（RR）和远紫外圆二色光谱测量，研究了在酸性pH条件下生成的细胞色素b(5)的CO复合物。在酸性pH（pH 3.1 - 3.5）下，还原态细胞色素b(5)与CO相互作用时，其Soret最大波长蓝移至420 nm，在540和570 nm左右观察到其他吸收带。在此条件下，铁 - 碳伸缩RR带在529 cm⁻¹处观察到（¹³CO为520 cm⁻¹），这表明形成了以组氨酸作为轴向配体的血红素 - CO加合物。在pH约为3.5时，血红素从还原态细胞色素b(5)蛋白上解离，而与N₂气氛相比，在CO气氛下其解离速率降低，这是由于形成了以组氨酸作为轴向配体的血红素 - CO加合物。
