Abstract
To examine the effects of π-stacking interactions between aromatic amino acid side chains and adenine bearing ligands in crystalline protein structures, 26 toluene/(N9-methyl) adenine model configurations have been constructed from protein/ligand crystal structures. Full geometry optimizations with the MP2 method cause the 26 crystal structures to collapse to six unique structures. The complete basis set (CBS) limit of the CCSD(T) interaction energies has been determined for all 32 structures by combining explicitly correlated MP2-R12 computations with a correction for higher-order correlation effects from CCSD(T) calculations. The CCSD(T) CBS limit interaction energies of the 26 crystal structures range from -3.19 to -6.77 kcal mol-1 and average -5.01 kcal mol-1. The CCSD(T) CBS limit interaction energies of the optimized complexes increase by roughly 1.5 kcal mol-1 on average to -6.54 kcal mol-1 (ranging from -5.93 to -7.05 kcal mol-1). Corrections for higher-order correlation effects are extremely important for both sets of structures and are responsible for the modest increase in the interaction energy after optimization. The MP2 method overbinds the crystal structures by 2.31 kcal mol-1 on average compared to 4.50 kcal mol-1 for the optimized structures. © 2008 American Chemical Society.
Recommended Citation
K. L. Copeland et al., "Probing Phenylalanine/Adenine Π-Stacking Interactions in Protein Complexes with Explicitly Correlated and CCSD(T) Computations," Journal of Physical Chemistry B, vol. 112, no. 45, pp. 14291 - 14295, American Chemical Society, Nov 2008.
The definitive version is available at https://doi.org/10.1021/jp805528v
Department(s)
Chemistry
International Standard Serial Number (ISSN)
1520-6106
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 American Chemical Society, All rights reserved.
Publication Date
13 Nov 2008
