Theoretical calculation of metalloprotein redox potential based on experimental 3-D structures

PHYS 364

Hui Li, hli4@unl.edu, Dejun Si, djsi@unlserve.unl.edu, and Nandun M. Thellamurege, nthella1@bigred.unl.edu. Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588
Relative redox potentials (E0) of type-1 Cu and Fe-S4 centers in 27 plastocyanins and 5 rubredoxins are calculated using quantum methods and chemical models extracted from experimentally determined 3D structures. The systematic or random differences in the x-ray structures can cause hundreds of mV differences in the computed E0. HF/6-31G* geometry optimization of 8, 22, 29, 41 and 67 atoms at the Cu center in 88-atom models for the 27 plastocyanins leads to maximum errors of about 500, 500, 230, 260 and 40 mV, respectively, and optimization of 61 atoms in 121-atom models leads to a maximum error of ~100 mV. B3LYP/6-31G* geometry optimization of 29 atoms at the Fe-S4 center in the 123-atom models for rubredoxins leads to an error of ~100 mV. It is very important to minimize these structural errors in computational analysis of protein redox potential regulation factors.
 

PHYS Poster Session - Multiscale Modeling in Biophysics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008