Local Conformational Transition of Hydrogenobacter thermophilus Cytochrome c552 Relevant to Its Redox Potential

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• 作者：Shin-ichi J. Takayama ; Yo-ta Takahashi ; Shin-ichi Mikami ; Kiyofumi Irie ; Shin Kawano ; Yasuhiko Yamamoto ; Hikaru Hemmi ; Ryo Kitahara ; Shigeyuki Yokoyama ; Kazuyuki Akasaka
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：August 14, 2007
• 年：2007
• 卷：46
• 期：32
• 页码：9215 - 9224
• 全文大小：316K
• 年卷期：v.46,no.32(August 14, 2007)
• ISSN：1520-4995

文摘

In order to elucidate the molecular mechanisms responsible for the apparent nonlinear behaviorof the temperature dependence of the redox potential of Hydrogenobacter thermophilus cytochrome c₅₅₂[Takahashi, Y., Sasaki, H., Takayama, S. J., Mikami, S., Kawano, S., Mita, H., Sambongi, Y., andYamamoto, Y. (2006) Biochemistry 45, 11005-11011], its heme active site structure has been characterizedusing variable-temperature and -pressure NMR techniques. The study revealed a temperature-dependentconformational transition between protein structures, which slightly differ in the conformation of the loopbearing the Fe-bound axial Met residue. The heme environment in the protein structure which arises atlower temperature was found to be more polar, as a result of the altered orientation of the loop withrespect to the heme due to its conformational change, than that arising at higher temperature. The presentstudy demonstrated the importance of the structural and dynamic properties of the polypeptide chain inclose proximity to the heme for redox regulation of the protein.