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백수연,강수진,Toshiharu Suzuki,Masasuke Yoshida,Toshimichi Fujiwara,Hideo Akutsu 한국자기공명학회 2013 Journal of the Korean Magnetic Resonance Society Vol.17 No.2
ATP synthase produces ATP, a major energy source for metabolic processes in organisms, from ADP and inorganic phosphate in cellular membranes. ATP synthase is known as a rotary motor, in which the c-subunit ring functions as a rotor. In this work, we have tried to develop a more general preparation procedure of thermophilic Foc-ring (TFoc-ring) for NMR measurements. The expression of TFoF1 is easily affected by various experimental conditions such as temperature, shape and size of a flask, a volume of medium, and shaking rate of an incubator. Accordingly, we have tried to optimize the expression conditions of TFoF1. TFoc-rings were purified from TFoF1 according to a reported method. We modified purification procedures to improve purity and yield of TFoc. On top of them, we found a new combination of detergents for the purification at anion-exchange column chromatography. To examine the effect of lipid environments on the structure, the TFoc-rings were reconstituted into two kinds of lipid bilayers, namely, saturated and unsaturated lipid ones. Then, we have compared characteristics of the TFoc-ring structures in these membranes with solid-state NMR
Bak, Suyeon,Kang, Su-Jin,Suzuki, Toshiharu,Yoshida, Masasuke,Fujiwara, Toshimichi,Akutsu, Hideo Korean Magnetic Resonance Society 2013 Journal of the Korean Magnetic Resonance Society Vol.17 No.2
ATP synthase produces ATP, a major energy source for metabolic processes in organisms, from ADP and inorganic phosphate in cellular membranes. ATP synthase is known as a rotary motor, in which the c-subunit ring functions as a rotor. In this work, we have tried to develop a more general preparation procedure of thermophilic $F_oc$-ring ($TF_oc$-ring) for NMR measurements. The expression of $TF_oF_1$ is easily affected by various experimental conditions such as temperature, shape and size of a flask, a volume of medium, and shaking rate of an incubator. Accordingly, we have tried to optimize the expression conditions of $TF_oF_1$. $TF_oc$-rings were purified from $TF_oF_1$ according to a reported method. We modified purification procedures to improve purity and yield of $TF_oc$. On top of them, we found a new combination of detergents for the purification at anion-exchange column chromatography. To examine the effect of lipid environments on the structure, the $TF_oc$-rings were reconstituted into two kinds of lipid bilayers, namely, saturated and unsaturated lipid ones. Then, we have compared characteristics of the $TF_oc$-ring structures in these membranes with solid-state NMR.
Takayama, Yuki,Taketa-Sato, Midori,Komori, Hirofumi,Morita, Kumiko,Kang, Su-Jin,Higuchi, Yoshiki,Akutsu, Hideo The Chemical Society of Japan 2011 Bulletin of the Chemical Society of Japan Vol.84 No.10
<P>Cytochrome <I>c</I><SUB>3</SUB> possesses four hemes in a compact configuration and exhibits extremely low reduction potentials. Besides the well-characterized factors contributing to the reduction potentials, the aromatic rings have been suggested to be involved. To elucidate its mechanism, the effect of mutations at conserved and noncoordinated aromatic residues on the reduction/oxidation properties of heme irons was investigated on the basis of crystal structures, NMR spectra of coordinated His, and reduction potentials. Phe20 parallel to heme 1 is the most conserved residue. On its mutation, the change in each coordination structure was subtle in the crystal structures despite of significant changes in the NMR spectra and reduction potentials. Significant increases in the reduction potentials of heme 1 led to the conclusion that the aromatic ring of Phe20 stabilizes the polarization of the π-electron density induced by the oxidized iron in the same heme. Furthermore, the reduction potential of heme 2 was also affected by the mutation at Phe20, revealing that the electrostatic interaction between the π-electron system of the porphyrin and a distant iron contributes to the iron reduction potential. This kind of interaction provides new insight into the role of the heme architecture in regulation of the reduction potentials.</P>