An artificial neural network analysis of porcine pancreas lipase catalysed esterification of anthranilic acid with methanol

Artificial neural network (ANN) analysis of porcine pancreas lipase (PPL) catalysed esterification of anthranilic acid with methanol was carried out. Methanol concentration, enzyme concentration, period of incubation, buffer volume and log P-values were the five important parameters employed. ANN analysis showed good correspondence between experimental and predicted values. The surface plots showed that methanol bound to PPL in preference to anthranilic acid. Compared to anthranilic acid (0.1 M) methanol was bound to PPL preferentially up to 0.5 M. Increase in enzyme concentration was found to enhance the extent of esterification in the concentration range 0.5–4.5 mg/mL of PPL. A similar increase in esterification was also observed in the presence of 0.05–0.35 mL of 0.1 M phosphate buffer at pH 7.0. The positive effect of the buffer indicated that imparting ‘pH memory’ to the enzyme enhanced the extent of esterification. Esterification increased also when it was carried out in non-polar solvents like n-heptane which has a log P-value of 4.0 compared to benzene (log P: 2.0) indicating that non-polar solvents were very effective in stabilising PPL especially when they contained a small amount of 0.1 M phosphate buffer at pH 7.0.