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Carbon dioxide: A waste product in the catalytic cycle of α-ketoglutarate dependent halogenases prevents the formation of hydroxylated by-products
, Article Journal of Physical Chemistry B ; Volume 113, Issue 1 , 2009 , Pages 12-14 ; 15206106 (ISSN) ; Latifi, R ; Sharif University of Technology
American Chemical Society
2009
Abstract
We present the first density functional theory study on α-ketoglutarate dependent halogenase and focus on the mechanism starting from the iron(IV)-oxo species. The studies show that the high-valent iron(IV)-oxo species reacts with substrates via an initial and rate determining hydrogen abstraction that is characterized by a large kinetic isotope effect (KIE) of 26.7 leading to a radical intermediate. This KIE value is in good agreement with experimental data. The reaction proceeds via two-state reactivity patterns on competing quintet and septet spin state surfaces with close lying hydrogen abstraction barriers. However the septet spin radical intermediate gives very high barriers for...