title: Time-resolved FTIR study of CO recombination with horseradish peroxidase.
abstract: Vibrational changes associated with CO recombination to ferrous horseradish peroxidase were investigated by rapid-scan FTIR (Fourier-transform IR) spectroscopy in the 1200-2200 cm(-1) range. At pH 6.0, two conformers of bound CO are present that appear as negative bands at 1905 and 1934 cm(-1) in photolysis spectra. Their recombination rate constants are identical, confirming that they arise from two substates of bound CO that are in rapid thermal equilibrium, rather than from heterogeneous protein sites. A smaller positive band at 2134 cm(-1) also appears on photolysis and decays with the same rate constant, indicative of an intraprotein geminate site involved in recombination or, possibly, a weak-affinity surface CO-binding site. Other signals arising from protein and haem in the 1700-1200 cm(-1) range can also be time-resolved with similar kinetics.
authors.affiliation: Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, London, UK.
authors.forename: Amandine
authors.initials: A
authors.lastname: Maréchal
authors.forename: W John
authors.initials: WJ
authors.lastname: Ingledew
authors.forename: Peter R
authors.initials: PR
authors.lastname: Rich
mesh_terms: D002248:Carbon Monoxide / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D007834:Lasers; D010782:Photolysis; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014732:Vibration
chemical_list: D002248:Carbon Monoxide; D007501:Iron; D006735:Horseradish Peroxidase