ISSN:
1075-4261
Keywords:
peroxidases
;
quantum-mixed spin
;
fluoride and hydroxyl complexes
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Physics
Notes:
Electronic absorption and resonance Raman spectra of ferric and ferrous forms of a peroxidase from soybean seed coat (SBP) at neutral and alkaline pH values together with the spectra of the ferric-fluoride complex are reported. At neutral pH a quantum mechanically mixed spin state, resulting from the admixture of intermediate spin, S = 3/2, and high spin, S = 5/2, configurations, has been identified which coexists with five- and six-coordinate high-spin hemes. A complete conversion to a fluoride-ligated six-coordinate high-spin and a hydroxy-ligated six-coordinate low-spin heme are observed at acid pH in the presence of fluoride and at alkaline pH, respectively. The spectral features suggest that both the fluoride and hydroxo ligands are stabilized by hydrogen-bond interactions with the distal Arg residue and through a water molecule with the distal His residue. The ferrous form shows a single ν(Fe - Im) at 246 cm-1 at neutral pH. The data indicate that SBP shares many characteristics with peroxidases belonging to class III of the “plant peroxidase” superfamily. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 355-364, 1998
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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