Hydration-aggregation pretreatment for drastically improving esterification activity of commercial lipases in non-aqueous media.

We investigated a novel, simple method for activating lipases in non-aqueous reaction media. Lipase powders were suspended in n-fatty alcohols and were then hydrated by adding a small amount of water. A paste-like aggregate was recovered from the mixture followed by lyophilization for obtaining activated lipases as dry powders. Lipase activity was evaluated for esterification between myristic acid and methanol in n-hexane. The activated lipases exhibited high esterification activity depending on the experiment conditions during hydration-aggregation pretreatment such as the amount of added water, the temperature, the pH of added buffer solutions, and the carbon chain length of the n-fatty alcohols used as pretreatment solvents. Various commercial lipases from different origins could be activated by this method. Changes in lipase conformation induced by the hydration-aggregation pretreatment were studied based on fluorescence and Fourier-transform infrared spectroscopy.