title: Monte Carlo and modified Tanford-Kirkwood results for macromolecular electrostatics calculations.
abstract: The understanding of electrostatic interactions is an essential aspect of the complex correlation between structure and function of biological macromolecules. It is also important in protein engineering and design. Theoretical studies of such interactions are predominantly done within the framework of Debye-Hückel theory. A classical example is the Tanford-Kirkwood (TK) model. Besides other limitations, this model assumes an infinitesimally small macromolecule concentration. By comparison to Monte Carlo (MC) simulations, it is shown that TK predictions for the shifts in ion binding constants upon addition of salt become less reliable even at moderately macromolecular concentrations. A simple modification based on colloidal literature is suggested to the TK scheme. The modified TK models suggested here satisfactorily predict MC and experimental shifts in the calcium binding constant as a function of protein concentration for the calbindin D(9k) mutant and calmodulin.
authors.affiliation: Departmento de Física, Instituto de Biociências, Letras e Ciências Extras, Universidade Estadual Paulista, 15054-000 - Rua Cristovão Colombo, 2265, Jd. Nazareth, São José do Rio Preto, SP, Brazil.
authors.forename: Sidney Jurado
authors.initials: SJ
authors.lastname: de Carvalho
authors.forename: Renato Carlos Tonin
authors.initials: RC
authors.lastname: Ghiotto
authors.forename: Fernando Luís Barroso
authors.initials: FL
authors.lastname: da Silva
mesh_terms: D046911:Macromolecular Substances / Q000737:chemistry*; D008962:Models, Theoretical; D009010:Monte Carlo Method; D055672:Static Electricity
chemical_list: D046911:Macromolecular Substances