Electrical fluctuations on the surfaces of proteins from hydrodynamic data

Area of Science:

• Biophysics
• Physical Chemistry
• Molecular Biology

Background:

• Proteins possess electrical properties on their surfaces.
• Understanding these properties is crucial for comprehending protein function and interactions.
• Previous research has not quantified these specific surface electrical characteristics.

Purpose of the Study:

• To calculate the electrical capacitance of protein surfaces.
• To estimate electrical fluctuations (charge, voltage, field, dipole moment) on protein surfaces.
• To develop predictive numerical equations for these surface properties based on molecular weight.

Main Methods:

• Calculation of electrical capacitance from hydrodynamic data.
• Estimation of electrical fluctuations using the fluctuation-dissipation theorem.
• Determination of polarizability from intrinsic viscosity to understand field and dipole fluctuations.
• Fitting capacitance, polarizability, and electrical fluctuations against protein molecular weight.

Main Results:

• Established numerical equations correlating protein molecular weight with surface capacitance, polarizability, and electrical fluctuations.
• Quantified charge fluctuations in fractions of unit charge.
• Quantified voltage fluctuations in the millivolt range.
• Quantified field fluctuations in the tens of mV/nm range.
• Quantified dipole moment fluctuations in the hundreds of times the water molecule's dipole moment range.

Conclusions:

• Successfully estimated key electrical surface properties of proteins.
• Developed predictive models for protein surface electrical characteristics based on molecular weight.
• These findings provide novel quantitative data on protein surface electrical behavior.