Oxygen Affinity Controlled by Dynamical Distal Conformations: The Soybean Leghemoglobin and the Paramecium caudatum Hemoglobin Cases

MARCELO A. MARTI; LUCIANA CAPECE; DAMIAN E. BIKIEL; BRUNO FALCONE; DARIO A. ESTRIN

PROTEINS: STRUCTURE, FUNCTION AND GENETICS

Año: 2007 vol. 68 p. 480 - 487

0887-3585

The binding of diatomic ligands, such as O2, NO, and CO to heme proteins is a process intimately related with their function. In this work we analyzed by means of a combination of classical Molecular Dynamics (MD) and Hybrid Quantum-Classical (QM/MM) techniques, the existence of multiple conformations in the distal site of heme proteins, and their influence on oxygen affinity regulation. We considered two representative examples: soybean leghemoglobin (Lba) and Paramecium caudatum truncated hemoglobin (PcHb). The results presented in this work provide a molecular interpretation for the kinetic, structural and mutational data that cannot be obtained by assuming a single distal conformation.