Molecular modeling studies of the DCCD-treated cytochrome bc1 complex: predicted conformational changes and inhibition of proton translocation.
Molecular modeling studies of the DCCD-treated cytochrome bc1 complex: predicted conformational changes and inhibition of proton translocation.
复制标题
DCCD 处理的细胞色素 bc1 复合物的分子模型研究：预测的构象变化和质子易位的抑制。
DOI：
10.1023/a:1015132323939
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发表时间：
2002
影响因子：
3
通讯作者：
Beattie,DianaS
中科院分区：
文献类型：
--
作者：
Wang,Yudong;Beattie,DianaS
Dicyclohexylcarbodiimide (DCCD) binds covalently to an acidic amino acid located in the cd loop connecting membrane-spanning helices C and D of cytochromebresulting in an inhibition of proton translocation in the cytochromebc1complex with minimal effects on the steady state rate of electron transfer. Single turnover studies performed with the yeast cytochromebc1complex indicated that the initial phase of cytochromebreduction was inhibited 25–45% in the DCCD-treated cytochromebc1complex, while the rate of cytochromec1reduction was unaffected. Simulations by molecular modeling predict that binding of DCCD to glutamate 163 located in the cd2 loop of cytochromebof chicken liver mitochondria results in major conformational changes in the protein. The conformation of the cd loop and the end of helix C appeared twisted with a concomitant rearrangement of the amino acid residues of both cd1 and cd2 loops. The predicted rearrangement of the amino acid residues of the cd loop results in disruptions of the hydrogen bonds predicted to form between amino acid residues of the cd and ef loops. Simultaneously, two new hydrogen bonds are predicted to form between glutamate 272 and two residues, aspartate 253 and tyrosine 272. Formation of these new hydrogen bonds would restrict the rotation and protonation of glutamate 272, which may be necessary for the release of the second electrogenic proton obtained during ubiquinol oxidation in the bc1complex.
