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Gramicidin derivatives as membrane-based pH sensors
Vitali Borisenko1, Zhihua Zhang, G Andrew Woolley
1Department of Chemistry, 80 St George Street, University of Toronto, M5S 3H6, Toronto, ON, Canada.
Biochimica Et Biophysica Acta
|December 26, 2001
Summary
Engineered gramicidin ion channels enable sensitive pH sensing at the molecular level. These modified channels exhibit pH-dependent behavior, allowing for precise measurements across various pH ranges.
Area of Science:
- Biophysics
- Molecular Biology
- Analytical Chemistry
Background:
- Ion channels are crucial for cellular processes and can be utilized for sensitive measurements.
- Gramicidin channels possess well-defined structures and functions, making them amenable to engineering.
Purpose of the Study:
- To engineer pH-sensitive gramicidin ion channel derivatives for molecular-level pH sensing.
- To characterize the pH-dependent behavior of these engineered channels.
Main Methods:
- Engineering of gramicidin ion channels with appended ethylenediamine and histamine groups.
- Analysis of single-channel behavior and thermal isomerization patterns.
- Correlating step sizes in recordings with the degree of protonation.
Main Results:
- Gramicidin-ethylenediamine and gramicidin-histamine derivatives showed pH-dependent single-channel activity in distinct ranges (pH 9-11 and 6.5-8.5, respectively).
- Thermal isomerization of carbamate groups induced step patterns in channel recordings.
- Step size directly correlated with the protonation state of the appended groups.
Conclusions:
- Engineered gramicidin channels offer a novel platform for single-molecule pH sensing.
- This method is effective for pH measurements under both symmetrical and gradient conditions.