APPLICATION OF 129I MOSSBAUER EFFECT TO BIOLOGICAL SYSTEMS: STUDIES WITH HEME MODELS*
AUTOR(ES)
Pasternak, M.
RESUMO
The Mossbauer effect associated with 129I, 125Te, and 57Fe has been applied to investigate structural properties of the axial ligands in ferric-high spin hematoheme-I, hematoheme-Te, and hematoheme-histidine-iodide. The magnitude and sign of the 129I quadrupole coupling constant (e2qQ) and the isomer shift, as deduced from the Mossbauer effect spectra, are consistent with an axial, s-p hybridized bond of overwhelming σ-character. Identical coupling constant (e2qQ(127I) = -1826 ± 3 MHz) were measured for both heme-I and hematoheme-histidine-iodide. Implications of this result to the nature of ferric-high spin heme-histidine complexing are discussed. A stable heme 125Te species formed in the electron-capture decay of heme-125I is observed, and structural properties of this singly bonded telluride ligand are discussed.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=335797Documentos Relacionados
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