Microhydration of Alanine in Gas Phase Studied by Quantum Chemical Method and ABEEM sigma pi/MM Fluctuating Charge Model

作者：Lu Li-nan; Liu Cui; Gong Li-dong^*

来源：Chemical Research in Chinese Universities, 2013, 29(2): 344-350.

DOI：10.1007/s40242-013-2158-z

• Alanine-water cluster
• ABEEM sigma pi/MM fluctuating charge model
• Quantum chemical calculation
• Hydrogen bond
• Interaction energy

A fluctuating charge interaction potential function for alanine-water was constructed in the spirit of newly developed ABEEM sigma pi/MM(atom-bond electronegativity equalization method at the sigma pi level fused into molecular mechanics). The properties of gaseous neutral alanine-(H2O)(n)(n=1-7) clusters were systematically investigated by quantum mechanics(QM) and the constructed ABEEM sigma pi/MM potential, such as conformations, hydrogen bonds (H-bonds), interaction energies, charge distributions, and so on. The results of ABEEM sigma pi/MM model are in fair agreement with those of QM and available experimental data. For isolated alanine, compared with those of experimental structure, the average absolute deviations(AAD) of bond length and bond angle are 0.002 nm and 1.4 degrees, respectively. For alanine-water clusters, the AAD of interaction energies and H-bond lengths are only 3.77 kJ/mol and 0.012 nm, respectively, compared to the results of MP2/aug-cc-pVDZ//MP2/6-311+G** method. The ABEEM sigma pi charges fluctuate with the changing conformation of the system, and can accurately and reasonably reflect the inter-polarization between water and alanine. The presented alanine-water potential function may provide a basis for further simulations on related aqueous solutions of biomolecules.

• 出版日期2013-4
• 单位辽宁师范大学