Journal article
The Role of Trp Side Chains in Tuning Single Proton Conduction through Gramicidin Channels
Biophysical journal, Vol.83(2), pp.880-898
2002
Handle:
https://hdl.handle.net/2376/105409
PMCID: PMC1302193
PMID: 12124271
Abstract
We present an extensive set of measurements of proton conduction through gramicidin A (gA), B (gB), and M (gM) homodimer channels which have 4, 3, or 0 Trp residues at each end of the channel, respectively. In gA we find a shoulder separating two domains of conductance increasing with concentration, confirming the results of Eisenman, G., B. Enos, J. Hagglund, and J. Sandblom. 1980.
Ann.
NY.
Acad.
Sci. 339:8–20. In gB, the shoulder is shifted by ∼½ pH unit to higher H
+ concentrations and is very sharply defined. No shoulder appears in the gM data, but an associated transition from sublinear to superlinear
I-
V values occurs at a 100-fold higher [H
+] in gM than in gA. The data in the low concentration domain are analyzed using a configuration space model of single-proton conduction, assuming that the difference in the proton potential of mean force (PMF) between gA and its analogs is constant, similar to the results of Anderson, D., R. B. Shirts, T. A. Cross, and D. D. Busath. 2001.
Biophys.
J. 81:1255–1264. Our results suggest that the average amplitudes of the calculated proton PMFs are nearly correct, but that the water reorientation barrier calculated for gA by molecular dynamics using the PM6 water model (Pomès, R., and B. Roux. 1997.
Biophys.
J. 72:246
a) must be reduced in amplitude by 1.5
kcal/mol or more, and is not rate-limiting for gA.
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Details
- Title
- The Role of Trp Side Chains in Tuning Single Proton Conduction through Gramicidin Channels
- Creators
- Joseph A Gowen - Zoology Department and Center for Neuroscience, Brigham Young University, Provo, Utah 84602Jeffrey C Markham - Zoology Department and Center for Neuroscience, Brigham Young University, Provo, Utah 84602Sara E Morrison - Zoology Department and Center for Neuroscience, Brigham Young University, Provo, Utah 84602Timothy A Cross - Center for Interdisciplinary Magnetic Resonance at the National High Field Laboratory, Institute of Molecular Biophysics and Department of Chemistry, Florida State University, Tallahassee, Florida 32306David D Busath - Zoology Department and Center for Neuroscience, Brigham Young University, Provo, Utah 84602Eric J Mapes - Department of Mathematics, Washington State University, Pullman, Washington 99164 USAMark F Schumaker - Department of Mathematics, Washington State University, Pullman, Washington 99164 USA
- Publication Details
- Biophysical journal, Vol.83(2), pp.880-898
- Academic Unit
- Mathematics and Statistics, Department of
- Publisher
- Elsevier Inc
- Identifiers
- 99900546722401842
- Language
- English
- Resource Type
- Journal article