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学科主题: 生命有机化学
题名: Effect of mutation at valine 61 on the three-dimensional structure, stability, and redox potential of cytochrome b5
其他题名: 第六十一位缬氨酸的突变对细胞色素b5法人三维结构、稳定性和氧化还原电位的影响
作者: Xue LL(薛林龙) ; Wang WH(王文虎) ; Xie Y(谢毅) ; Yao P(姚萍) ; Wang YH(王韵华) ; Qian W(钱雯) ; Huang ZX(黄仲贤) ; Wu J(邬健) ; Xia ZX(夏宗芗)
通讯作者: 夏宗芗
刊名: Biochemistry
发表日期: 1999-01-01
卷: 38, 期:37, 页:11961-11972
收录类别: SCI
部门归属: 复旦大学; 中国科学院上海有机化学研究所生命有机国家开放实验室
英文摘要: To elucidate the role played by Val61 of cytochrome b5, this residue of the tryptic fragment of bovine liver cytochrome b5 was chosen for replacement with tyrodine (Val6a Tyr), histidine (V al61His), glutamic acid (Val61Glu), and lysine (Valt1Lys) by means of site-directed mutagenesis. The mutants Val61Tyr, Val61Glu Val61His, and Val61Lys exhibit electronic spectra identical to that of the wild type, suggesting that mutation at Val61 did not affect the overall protein structure significantly. The redox potentials determined by differential pulse voltammetry were -10 (wild type), -25 (Val61Glu), -33 (Val61Tyr) 12 (Val61His), and 17mV(Val61Lys) versus NHE. The thermal stabilities and urea-mediated denaturation of wild-type cytochrome b5 and its mutants werein the following order: wild type> Val61Glu> Val61Tyr> Val61His> Val61Lys. The kinetics of denaturation of cytochrome b5 by urea was also analyzed. The first-order rate constants of heme transfer between cytochrom b5 and apomyoglobin at 20±0.2℃were 02.5℃±0.01(wildtype),0.42±0.02(valt1Tyr(, 0.93±0.04(Val61Glu),2.88±0.01(Val61His),and 3.88±0.02H^-1(Val61Lys). The crystal sturcture of Val61His was determined using the molecular replacement method and refined at 2.1 A resolution, showing that the imidazole side chain of His61 points away from the heme-binding pocket and extends into the solvent, the coordination distances from Fe to NE2 atoms of two axial ligands are approximately 0.6 A longer than the reported value, and the hydrogen bond network involving Val61, the heme propionates, and three water molecules no longer exists. We conclude that the conserved residue Val61,the heme propionates,The "electrostatic potential" around the heme-exposed area and the hydrophobicity of the heme pocket are determinant factors modulating the redox potential of cytochrome b5, and the hydrogen bond network around the exposed heme edge is also and important factor affecting the heme stability.
语种: 英语
相关网址: 查看原文
内容类型: 期刊论文
URI标识: http://ir.sioc.ac.cn/handle/331003/23656
Appears in Collections:生命有机化学国家重点实验室_期刊论文

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Recommended Citation:
Xue LL,Wang WH,Xie Y,et al. Effect of mutation at valine 61 on the three-dimensional structure, stability, and redox potential of cytochrome b5[J]. Biochemistry,1999,38(37):11961-11972.
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