STEP-SCAN FT-IR TIME-RESOLVED SPECTROSCOPY (S-2 FT-IR DELTA-A TRS) OFTHE PHOTODYNAMICS OF CARBONMONOXY-MYOGLOBIN

The kinetics of protein response and of CO recombination after photoly sis 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 simult aneous 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 a nd kinetic data corroborate and confirm previously published single fr equency infrared studies indicating that the rebinding process is acco mplished 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.