High-field Mössbauer studies of reduced protocatechuate 3,4-dioxygenase

R. Zimmermann, B. H. Huynh, E. Münck, John D Lipscomb

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Abstract

We have studied the Mössbauer spectra of reduced protocatechuate 3,4-dioxygenase (3,4-PCase) from P. aeruginosa in the temperature range from 1.5 to 200 K in applied magnetic fields up to 55 kG. The entire data set was fitted to a spin Hamiltonian pertinent to the high-spin ferrous ion. By judiciously choosing the experimental conditions, the multiparameter problem could be solved rather unambiguously. The iron sites of reduced 3,4-PCase are characterized by a negative zero-field splitting parameter D = -(6±1) cm-1 and a large rhombicity E/D = 0.25±0.05. The data show clearly that the electric field gradient tensor is rotated relative to the zero-field splitting, suggesting a point symmetry of monoclinic or lower. The electronic spin relaxation rate, at 4.2 K, is slower than 107 s-1.

Original languageEnglish (US)
Pages (from-to)5463-5467
Number of pages5
JournalThe Journal of chemical physics
Volume69
Issue number12
DOIs
StatePublished - Jan 1 1978

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