Volume 20, Issue 13 pp. 1401-1411

Modeling β-lactam interactions in aqueous solution through combined quantum mechanics–molecular mechanics methods

Jesús Pitarch

Jesús Pitarch

Departamento de Química Física, Universidad de Valencia, 46100 Burjasot (Valencia), Spain

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Juan-Luis Pascual–Ahuir

Juan-Luis Pascual–Ahuir

Departamento de Química Física, Universidad de Valencia, 46100 Burjasot (Valencia), Spain

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Estanislao Silla

Corresponding Author

Estanislao Silla

Departamento de Química Física, Universidad de Valencia, 46100 Burjasot (Valencia), Spain

Departamento de Química Física, Universidad de Valencia, 46100 Burjasot (Valencia), SpainSearch for more papers by this author
Iñaki Tuñón

Iñaki Tuñón

Departamento de Química Física, Universidad de Valencia, 46100 Burjasot (Valencia), Spain

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Manuel F. Ruiz–López

Manuel F. Ruiz–López

Laboratoire de Chimie Théorique, UMR CNRS-UHP 7565, Institut Nancéien de Chimie Moléculaire, Université Henri Poincaré-Nancy I, BP 239, 54506 Vandoeuvre-lès-Nancy, France

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Abstract

In this article, we have carried out a series of theoretical computations intended to analyze the interactions of β-lactam compounds in aqueous solution. The final aim is to rationalize the influence of the medium on β-lactam antibiotics reactivity. In particular, the hydrolysis reaction has been studied because of the considerable interest due to its relationship with resistance mechanisms developed by bacteria. The study is extended to the simplest β-lactam molecule, propiolactam or 2-azetidinone, and to the corresponding hydroxylated complex (resulting from the addition of a hydroxyl anion to the carbonyl group) that plays a crucial role in hydrolysis processes. Molecular Dynamics simulations have been carried out using a hybrid quantum mechanics–molecular mechanics potential: the solute is described using the density functional theory, whereas water solvent molecules are treated classically. This represents a sophisticated computational level which, compared to usual force-field simulations, has the advantage of allowing a detailed analysis of solute's electronic properties. The discussion of results is focused on the role played by solute–solvent hydrogen bonds and solvent fluctuations on solute's structure. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1401–1411, 1999

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