Exhibits significant esterase activity with a preference for short acyl chain esters (C4-C8) in vitro. Its physiological function is not known. Displays neither proteolytic activity using casein as substrate, nor peptidase activity when assayed with L-leucine p-nitroanilide and L-proline p-nitroanilide. a carboxylic ester + H2O = a carboxylate + an alcohol + H(+) Is strongly inhibited by phenylmethylsulfonyl fluoride, a serine protease inhibitor, and by mercury chloride. Diethyl pyrocarbonate, a histidine modifier, also inhibits the reaction, albeit less pronounced than phenylmethylsulfonyl fluoride. EDTA and dithiothreitol have no effect on enzyme activity. kcat is 1.0 sec(-1) with pNP-acetate as substrate. kcat is 14.9 sec(-1) with pNP-butyrate as substrate. kcat is 10.2 sec(-1) with pNP-valerate as substrate. kcat is 1.6 sec(-1) with pNP-octanoate as substrate. kcat is 1.3 sec(-1) with pNP-decanoate as substrate (at pH 7 and 70 degrees Celsius). Optimum pH is 7. Optimum temperature is around 95 degrees Celsius. Shows >70% of its maximal activity in the pH range of 5-9. Displays a relatively high thermostability with a half-life of 1 hour at 100 degrees Celsius. Exists mainly as a monomer and, to some extent as a dimer. The high thermal stability and activity in the presence of organic solvents makes EstD an attractive catalyst for future applications in industry. Belongs to the AB hydrolase superfamily. Esterase 10 family.