Interaction of halides with the cyanide complex of myeloperoxidase: a model for substrate binding to compound I.
EPR spectra of the low-spin cyanide complex of myeloperoxidase have been measured in the absence and presence of halide substrates; chloride, bromide and iodide. Halide-dependent spectral changes are found at acidic pH. The electronic structure of the low-spin ferric iron in cyanide complex appears to be modulated by halide binding to a protonated amino acid in the distal heme cavity. These findings suggest halide substrates can interact with ferryl oxygen in compound I during enzyme catalysis to form hypohalous acid.
Lee
H C
HC
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia.
Booth
K S
KS
Caughey
W S
WS
Ikeda-Saito
M
M
D001965:Bromides / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003486:Cyanides / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D007454:Iodides / Q000378:metabolism*; D007700:Kinetics; D009195:Peroxidase / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
D001965:Bromides; D002712:Chlorides; D003486:Cyanides; D007454:Iodides; D009195:Peroxidase