These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: pKa analysis for the zinc-bound water in human carbonic anhydrase II: Benchmark for "multiscale" QM/MM simulations and mechanistic implications.
    Author: Riccardi D, Cui Q.
    Journal: J Phys Chem A; 2007 Jul 05; 111(26):5703-11. PubMed ID: 17506534.
    Abstract:
    To quantitatively explore the applicability of the generalized solvent boundary potential (GSBP) based QM/MM approach as a "multiscale" framework for studying chemical reactions in biomolecules, the structural and energetic properties of the Human Carbonic Anhydrase II (CAII) are analyzed and compared to those from periodic boundary condition (PBC) simulations and available experimental data. Although the atomic fluctuations from GSBP based simulations are consistently lower compared to those from PBC simulations or crystallographic data, the fluctuations and internal coordinate distributions for residues in the proximity of the active site as well as diffusion constants of active-site water molecules are fairly well described by GSBP simulations. The pKa of the zinc-bound water, calculated with a SCC-DFTB/MM-GSBP based thermodynamic integration approach, agrees well with experiments for the wild type CAII. For the E106Q mutant, however, a 9 pKa unit downward shift relative to the wild type is found in contrast with previous experiments that found little change. This dramatic discrepancy signals a possible change in the mechanism for the interconversion between CO2/HCO3- in the E106Q mutant, which may be similar to the bicarbonate mediated mechanism proposed for the Co2+ substituted CAII (J. Am. Chem. Soc. 2001, 123, 5861).1 The study highlights pKa analyses as a valuable approach for quantitatively validating the computational model for complex biomolecules as well as for revealing energetic properties intimately related to the chemical process of interest.
    [Abstract] [Full Text] [Related] [New Search]