Electrostatic properties of bovine beta-lactoglobulin

Bovine beta-Lactoglobulin (BLG) has been studied for many decades, but only recently structural data have been obtained, making it possible to simulat e its molecular properties. in the present study, electrostatic properties of BLG are investigated theoretically using Poisson-Boltzmann calculations and experimentally following pH titration via NMR. Electrostatic properties are determined for several structural models, including an. ensemble of NM R structures obtained at low pH. The changes in electrostatic forces upon c hanges in ionic strength, solvent dielectric constant, and pH are calculate d and compared with experiments. pH(a)s are computed for all titratable sit es and compared with NMR titration data. The analysis of theoretical and ex perimental results suggests that (1) there may be more than one binding sit es for negatively charged ligands; (2) at low pH the core of the molecule i s more compact than observed in the structures obtained via restrained mole cular dynamics from NMR data, but loop and terminal regions must be disorde red. (C) 2000 Wiley-Liss, Inc.