(180af) Molecular Dynamics of Pseudomonas Cepacia Lipase in Different Buffers and Correlations with Its Biocatalytic Activity

Variyath, S., University of Cincinnati
Kim, J., University of Cincinnati
Guliants, V., University of Cincinnati

Lipase from Pseudomonas cepacia (EC (PcL) is one of the most versatile biocatalysts used in various industries, such as food, oleochemicals and pharmaceuticals. For these practical applications, the optimization of its biocatalytic behavior is essential. Providing a favorable micro-environment can enhance biocatalytic activity of this lipase. Consequently, the suitable selection of buffer components is highly important for the practical applications of this biocatalyst. In particular, the specific ion effect has not been elucidated fully for the enzyme activity because of its complicated nature.

In this study, the specific cation effect on the hydrolytic activity of PcL has been investigated for the NaCl, KCl, CaCl2, NaH2PO4 and K2HPO4 buffer solutions under ambient conditions employing molecular dynamics (NAMD) and experimental biocatalytic activity assays. The PME (Particle Mesh Algorithm) was used to describe the long range interactions of the cations with the enzyme employing the CHARMM force field with explicit water (TIP3P) solvent. The motions of each residue in the catalytic triad (Ser87, Asp264 and His286) and lid domains of the enzyme have been investigated by these computational methods. Experimentally, the specific activities of the enzyme were measured by a colorimetric assay of p-nitrophenyl acetate hydrolysis. The specific ion effects for PcL activity under different solution pH and ionic strength have been demonstrated by the molecular dynamics simulations.