New Submission Effect of uniformly charged lipid film on the hydrodynamic radius of charged biopolymers

The functionality of proteins and other biopolymers in living cell depends on its secondary structure. The variation in the physical parameters like charge distribution, temperature, pressure, pH conditions in the immediate surroundings can alter the secondary structure and conformation of proteins.  Among these factors, the electrostatic interactions between biopolymers and charged lipid membrane play an important role in the protein folding.

In present work, we discuss the effect of the charged membrane on the protein conformation in an electrolyte solution. Our analysis shows that the hydrodynamic radius of proteins is affected by the charge density of the lipid membrane.  We have proposed a model to obtain an analytical equation relating the variation in the hydrodynamic radius of a charged polymer (like proteins) and the charge density of a uniformly charged Langmuir monolayer (like in cell membrane) due to electrical interactions. The validity of the equation was verified by experimental investigations on variation of hydrodynamic radius of heat shock protein molecules in the vicinity of Langmuir monolayer of charged lipids as a function of charge density. We also propose and demonstrate a novel method to find the deformation constant of proteins/biopolymers.