Effect of Glu-143 and His-231 substitutions on the catalytic activity and secretion of Bacillus subtilis neutral protease

Abstract

Molecular dynamics simulations have been used to model the motions and conformational behavior of the whey protein bovine ß-lactoglobulin. Simulations were performed for the protein by itself and complexed to a single retinol ligand located in a putative interior binding pocket. In the absence of the retinol ligand, the backbone loops around the opening of this ulterior pocket shifted inward to partially close off this cavity, similar to the shifts observed in previously reported molecular dynamics simulations of the uncomplexed form of the homologous retinol binding protein. The protein complexed with retinol does not exhibit the same conformational shifts. Conformational changes of this type could serve as a recognition signal allowing in vivo discrimination between the free and retinol complexed forms of the 3-lactoglobulin molecule. The unusual bending of the single a-helix observed in the simulations of retinol binding protein were not observed in the present calculations