Monovalent cation transport: Lack of structural deformation upon cation binding

Fang Tian, K. C. Lee, W. Hu, T. A. Cross

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

Cations often deform the structure of regulatory proteins to affect a functional response, but for other protein functions a more passive effect is desired. For instance, it is shown here that in the conductance of Na+ by the gramicidin channel there appears to be no significant structural deformation of either the side chains or backbone upon Na+ binding in the channel. This is based on 15N and 13C chemical shifts, 2H quadrupolar interactions, and 15N-2H dipolar interactions obtained by solid-state NMR spectroscopy of uniformly aligned lipid bilayer preparations of the gramicidin channel in the presence and absence of Na+. This conclusion is despite some significant changes in the 15N(α) and 13C1 chemical shift values which are argued here to be the result of indirect polarization effects upon cation binding rather than reflections of structural and dynamic changes. The lack of structural deformation implies that Na+ moves to the carbonyl oxygens lining the pore of this channel for solvation rather than the carbonyl groups moving in toward the channel axis. This forces the cartons onto a helical path following the positions of the carbonyl oxygens around the channel pore. Furthermore, an ideal binding site geometry for Na+ in the channel is avoided. Instead, adequate binding energy is provided by the channel to compensate for the loss of hydration energy when the cations enter the channel. The avoidance of strong binding ensures that efficient transport of the cations through the channel can be realized.

Original languageEnglish (US)
Pages (from-to)11959-11966
Number of pages8
JournalBiochemistry
Volume35
Issue number37
DOIs
StatePublished - Sep 30 1996

Fingerprint

Monovalent Cations
Cations
Gramicidin
Chemical shift
Oxygen
Lipid bilayers
Solvation
Lipid Bilayers
Binding energy
Linings
Hydration
Nuclear magnetic resonance spectroscopy
Proteins
Magnetic Resonance Spectroscopy
Binding Sites
Polarization
Geometry

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Tian, Fang ; Lee, K. C. ; Hu, W. ; Cross, T. A. / Monovalent cation transport : Lack of structural deformation upon cation binding. In: Biochemistry. 1996 ; Vol. 35, No. 37. pp. 11959-11966.
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Monovalent cation transport : Lack of structural deformation upon cation binding. / Tian, Fang; Lee, K. C.; Hu, W.; Cross, T. A.

In: Biochemistry, Vol. 35, No. 37, 30.09.1996, p. 11959-11966.

Research output: Contribution to journalArticle

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T2 - Lack of structural deformation upon cation binding

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AU - Lee, K. C.

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AU - Cross, T. A.

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