A novel, versatile family IV carboxylesterase exhibits high stability and activity in a broad pH spectrum.

Abstract

To investigate the properties of a novel metagenome-derived member of the hormone-sensitive lipase family of lipolytic enzymes. A forest soil metagenome-derived gene encoding an esterase (Est06) belonging to the hormone-sensitive lipase family of lipolytic enzymes was subcloned, heterologously expressed and characterized. Est06 is a polypeptide of 295 amino acids with a molecular mass of 31kDa. The deduced protein sequence shares 61% similarity with a hypothetical protein from the marine symbiont Candidatus Entotheonella sp. TSY1. Purified Est06 exhibited high affinity for acyl esters with short-chain fatty acids, and showed optimum activity with p-nitrophenyl valerate (C5). Maximum enzymatic activity was at 50°C and pH 7. Est06 exhibited high stability at moderate temperatures by retaining all of its catalytic activity below 30°C over 13days. Additionally, Est06 displayed high stability between pH 5 and 9. Esterase activity was not inhibited by metal ions or detergents, although organic solvents decreased activity. The combination of Est06 properties place it among novel biocatalysts that have potential for industrial use including low temperature applications.