title: Transient Raman study of horseradish peroxidase. Evidence for a lack of extensive heme pocket relaxation subsequent to carbon monoxide photolysis.
abstract: Time-resolved resonance Raman spectroscopy is a valuable tool for the study of the dynamics of heme-protein interactions. In particular, the photolysis of a ligand by short laser pulses allows for the examination of the dynamic evolution of heme-protein interactions subsequent to ligand dissociation. To date, such studies have been confined largely to hemoglobins and myoglobins. Here we present the results of the first transient Raman study of a peroxidase. Resonance Raman spectra of horseradish peroxidase were obtained within 10 ns of ligand (CO) photolysis at a variety of pH values. We find that there is only minimal relaxation of the heme pocket of horseradish peroxidase in response to ligand photolysis. This relaxation is pH-dependent and most probably involves the heme vinyl substituents. Such behavior is in sharp contrast to the transient behavior of most hemoglobins and beef heart cytochrome oxidase.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002248:Carbon Monoxide / Q000378:metabolism*; D002417:Cattle; D003576:Electron Transport Complex IV / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology; D009211:Myoglobin / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman / Q000379:methods; D013329:Structure-Activity Relationship
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; D006418:Heme; D002248:Carbon Monoxide; D006735:Horseradish Peroxidase; D010544:Peroxidases; D003576:Electron Transport Complex IV