Myoglobin Recombination at Low Temperatures: Two Phases Revealed by FTIR Spectroscopy
22 February 1987
The low-temperature recombination of CO with myoglobin was studied using Fourier transform infrared spectroscopy. The bound state of MbCO has two distinct conformers observed at 1925.5 and 1945cm-1 with an intensity ratio of 1 to 8. The recombination of these bands after complete photolysis at 10K followed by a temperature jump shows distinct kinetics for the two bands. The 1945cm -1 band apparently follows the non-exponential kinetics originally described by Frauenfelder et al. (Austin et al., Biochemistry, 1975, v.14, p. 5355-5373.) But, the 1925cm sup -1 band does not appear appreciably below 70 K and appears with simple exponential kinetics at 80K and above.