R-state hemoglobin bound to heterotropic effectors:: models of the DPG, IHP and RSR13 binding sites

We performed a docking study followed by a 500-ps molecular dynamics simulation of R-state human adult hemoglobin (HbA) complexed to different heterotropic effectors [2,3-diphosphoglycerate (DPG), inositol hexaphosphate (IHP), and 2-[4-[(3,5-dichlorophenylcarbamoyl)-[methyl]-phenoxy]-2-meth- ylpropionic acid (RSR13)) to propose a molecular basis for recently reported interactions of effectors with oxygenated hemoglobin. The simulations were carried out with counterions and explicit solvation. As reported for T-state HbA, the effector binding sites are also located in the central cavity of the R-state and differ depending on effector anionic character. DPG and IHP bind between the alpha-subunits and the RSR13 site spans the alpha(1)-, alpha(2)- and beta(2)-subunits. The generated models provide the first report of the molecular details of R-state HbA bound to heterotropic effectors. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.