Myoglobin-CO Conformational Substate Dynamics: 2D Vibrational Echoes and MD Simulations

Abstract Two-dimensional (2D) infrared vibrational echoes were performed on horse heart carbonmonoxymyoglobin (MbCO) in water over a range of temperatures. The A 1 and A 3 conformational substates of MbCO are found to have different dephasing rates with different temperature dependences. A frequency–frequency correlation function derived from molecular dynamics simulations on MbCO at 298K is used to calculate the vibrational echo decay. The calculated decay shows substantial agreement with the experimentally measured decays. The 2D vibrational echo probes protein dynamics and provides an observable that can be used to test structural assignments for the MbCO conformational substates.