Modeling gating charge and voltage changes in response to charge separation in membrane proteins

Area of Science:

• Biophysics
• Computational Biology
• Electrochemistry

Background:

• Voltage changes in membrane proteins reveal charge transport mechanisms.
• Interpreting these voltage changes for charge equivalents and distances is challenging.
• Existing continuum models have uncertainties, and microscopic simulations are limited.

Purpose of the Study:

• To develop and validate a coarse-grained model for simulating voltage generation in membrane proteins.
• To accurately evaluate gating charges and electrode potentials during charge transfer.
• To provide a reliable method for interpreting experimental voltage measurements.

Main Methods:

• A coarse-grained model was developed, explicitly including the membrane, electrolytes, and electrodes.
• The model simulates gating charges and electrode potentials resulting from charge transfer.
• Model accuracy was validated against experimental voltage changes in bacterial photosynthetic reaction centers.

Main Results:

• The coarse-grained model successfully reproduced experimental voltage changes associated with electron and proton transfer.
• The calculations demonstrated the model's general applicability to membrane protein charge transport.
• Different spatial charge separation directions yielded similar voltage changes, highlighting interpretation complexities.

Conclusions:

• The developed coarse-grained model offers a reliable approach for studying charge transport in membrane proteins.
• The findings emphasize the need for careful interpretation of voltage changes, as spatial direction can influence observed signals.
• This method advances the understanding of fundamental charge displacement processes in biological systems.