期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 133, 期 9, 页码 2860-2863出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja1116414
关键词
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资金
- Japanese Ministry of Education, Culture, Sports, Science, and Technology [22247024, 20108014, 22770159, 21023014, 19042013, 18074003]
- Grants-in-Aid for Scientific Research [21023014, 22247024, 22770159, 20108014, 19042013, 20108001, 18074003] Funding Source: KAKEN
V-ATPase from Enterococcus hirae forms a large supramolecular protein complex (total molecular weight similar to 700 000) and physiologically transports Na(+) and Li(+) across a hydrophobic lipid bilayer. Stabilization of these cations in the binding site has been discussed on the basis of X-ray crystal structures of a membrane-embedded domain, the K-ring (Na(+)- and Li(+)-bound forms). Here, sodium or lithium ion-binding-induced difference IR spectra of the intact V-ATPase have for the first time been measured at physiological temperature under a sufficient amount of hydration. The results suggest that sodium or lithium ion binding induces the deprotonation of Glu139, a hydrogen-bonding change in the tyrosine residue, and a small conformational change in the K-ring. These structural changes, especially the deprotonation of Glu139, are considered to be important for reducing energetic barriers to the transport of cations through the membrane.
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