Step-Scan FT-IR Time-Resolved Spectroscopy (S2 FT-IR ΔA TRS) of the Photodynamics of Carbonmonoxy-myoglobin

Abstract

The kinetics of protein response and of CO recombination after photolysis of the Fe-CO bond in carbonmonoxy-myoglobin have been monitored by step-scan FT-IR absorption difference time-resolved spectroscopy (SZ FT-IR Delta A TRS) in D2O solution at ambient temperature. From simultaneous measurement of changes in nu CO and in the amide I band it has been possible to correlate the CO recombination kinetics with protein secondary structural changes with mu s time resolution. The spectral and kinetic data corroborate and confirm previously published single frequency infrared studies indicating that the rebinding process is accomplished with only minimal change in the protein secondary structure. Data of higher temporal resolution (to 20 ns) have also been obtained for the CO recombination process.