TY - JOUR
T1 - Structural changes of the KcsA potassium channel upon application of the electrode potential studied by surface-enhanced IR absorption spectroscopy
AU - Yamakata, Akira
AU - Shimizu, Hirofumi
AU - Osawa, Masatoshi
AU - Oiki, Shigetoshi
N1 - Funding Information:
This work was partly supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant-in-Aid for Priority Areas 477, “Molecular Science for Supra Functional Systems”) (A. Y.: 22018002, 20050002, H. S.: 22018007, 20050010). A. Y. is grateful for the valuable discussion with Prof. Hirotsugu Hiramatsu of Tohoku University.
PY - 2013
Y1 - 2013
N2 - Structural changes of the KcsA potassium channel fixed on gold electrode surface in the upright orientation were studied by surface-enhanced IR absorption spectroscopy (SEIRAS). Measurements were performed at neutral pH, where the activation gate is kept closed. Band intensities were enhanced for the asymmetric (1565 cm-1) and symmetric (1405 cm-1) OCO-carboxylate groups at negative electrode potentials in the K+ solution, but not in the Na+ solution. Even for the reverse-oriented channel, the enhanced OCO-carboxylate band was evident at negative potential. When TBA was loaded in the central cavity, the K+-specific OCO band was not elicited. These results indicate that the negative electrode potential renders the local K+ concentration accumulated at the vicinity of the electrode surface, and the KcsA channel bathed in high K+ changes conformation of the selectivity filter from the collapsed to the open, and OCO-carboxylate groups (D80 and E71) in the back of the filter were rearranged. Crown
AB - Structural changes of the KcsA potassium channel fixed on gold electrode surface in the upright orientation were studied by surface-enhanced IR absorption spectroscopy (SEIRAS). Measurements were performed at neutral pH, where the activation gate is kept closed. Band intensities were enhanced for the asymmetric (1565 cm-1) and symmetric (1405 cm-1) OCO-carboxylate groups at negative electrode potentials in the K+ solution, but not in the Na+ solution. Even for the reverse-oriented channel, the enhanced OCO-carboxylate band was evident at negative potential. When TBA was loaded in the central cavity, the K+-specific OCO band was not elicited. These results indicate that the negative electrode potential renders the local K+ concentration accumulated at the vicinity of the electrode surface, and the KcsA channel bathed in high K+ changes conformation of the selectivity filter from the collapsed to the open, and OCO-carboxylate groups (D80 and E71) in the back of the filter were rearranged. Crown
KW - Electrochemistry
KW - KcsA potassium channel
KW - Potassium-induced structure changes
KW - Surface-enhanced ir absorption spectroscopy
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U2 - 10.1016/j.chemphys.2013.02.035
DO - 10.1016/j.chemphys.2013.02.035
M3 - Article
AN - SCOPUS:84882270087
SN - 0301-0104
VL - 419
SP - 224
EP - 228
JO - Chemical Physics
JF - Chemical Physics
ER -