Molecular shielding of electric field complex dissociation

Area of Science:

• Biophysics
• Molecular Biology
• Electrochemistry

Background:

• Cell membranes generate electric fields capable of dissociating molecular complexes.
• Previous work demonstrated dissociation of ascorbate and catecholamines up to 8 nm from cell membranes.

Purpose of the Study:

• To investigate the applicability of electric field-induced dissociation to a broader range of biological complexes.
• To establish a method for estimating dissociation constants and association energies using electric field dependence.
• To explore the relationship between molecular size, shielding, and electric field effects on complex dissociation.

Main Methods:

• Applying electric fields to various biological complexes, including small molecule-small molecule, protein-protein, and small molecule-protein pairs.
• Measuring the electric field dependence of complex dissociation.
• Extrapolating the electric field dependence to zero electric field to determine dissociation constants (K(D)).
• Calculating association energy (E) from log(K(D)).
• Analyzing the relationship between the electric field dependence slope and molecular radii (r1, r2).

Main Results:

• Electric field-induced dissociation is effective for diverse biological complexes (norepinephrine-morphine sulfate, insulin-glucagon, epinephrine-bovine serum albumin).
• The method allows estimation of log(K(D)) and association energy (E).
• The slope of electric field dependence is inversely proportional to molecular radii, indicating molecular shielding.
• A molecular shielding constant of 7.04 x 10(-8) cm2/V was determined.
• Large complexes experience minimal electric field effects due to shielding and restricted membrane proximity.

Conclusions:

• Cell membrane electric fields play a significant role in the dissociation of various biological complexes.
• Molecular size and shielding are critical factors determining the susceptibility of complexes to electric fields.
• Understanding these electric field interactions is crucial for comprehending molecular binding and receptor function at the cell membrane.