Computational Quantification of the Physicochemical Effects of Heme Distortion: Redox Control in the Reaction Center Cytochrome Subunit of Blastochloris viridis.
File Type:
PDFItem Type:
Journal ArticleDate:
2013Access:
OpenAccessCitation:
Macgowan SA, Senge MO, Computational Quantification of the Physicochemical Effects of Heme Distortion: Redox Control in the Reaction Center Cytochrome Subunit of Blastochloris viridis., Inorganic chemistry, 52, 3, 2013, 1228-37Download Item:
MS245-Tara.pdf (Published (author's copy) - Peer Reviewed) 1.567Mb
Abstract:
A facile, experimentally calibrated computational procedure is described that
affords the relative ordering of heme cofactor reduction potentials with respect to intrinsic shifts
brought about by apoprotein induced heme-macrocycle distortion. The method utilizes heme-Fe
partial atomic charges and is useful with the computationally inexpensive B3LYP/3-21g method
calculated for simplified heme models extracted from the Protein Data Bank incorporating only
the effects of varying macrocycle conformations and thereby delineating their physicochemical
effects. The procedure was successfully calibrated using the atomic coordinates and published mid-point potentials from the heme cofactors in wild-type and a series of heme-NO and ?O2
binding domain mutants and thus confirmed the sole conformational modulation of the redox
potentials in these complexes. This technique was also applied to the reaction center tetraheme
cytochrome subunit of Blastochloris viridis to build upon previous work elucidating the role that
conformational control plays in photosynthetic systems and it was found that this effect may
account for up to 70% (54mv) of the observed differences in the reduction potentials of the four
hemes. We validate the approach using larger basis sets up to and including the triple-?, doubly
polarized and augmented 6-311+g** basis and discuss the specific conformational origins of the
effect.
Author's Homepage:
http://people.tcd.ie/sengemhttp://people.tcd.ie/macgowsa
Description:
PUBLISHED
Author: MACGOWAN, STUART ALEXANDER; SENGE, MATHIAS
Type of material:
Journal ArticleCollections:
Series/Report no:
Inorganic chemistry;52;
3;
Availability:
Full text availableLicences: