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.
Conference Article| November 19 2008
Time-resolved FTIR study of CO recombination with horseradish peroxidase
W. John Ingledew;
Peter R. Rich
Peter R. Rich 1
*Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1 6BT, U.K.
1To whom correspondence should be addressed (email email@example.com).
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Amandine Maréchal, W. John Ingledew, Peter R. Rich; Time-resolved FTIR study of CO recombination with horseradish peroxidase. Biochem Soc Trans 1 December 2008; 36 (6): 1165–1168. doi: https://doi.org/10.1042/BST0361165
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