Highest overexpression of an esterase from Streptomyces diastatochromogenes (EstA) cloned into E. coli was achieved using a rhamnose-inducible promotor. Highest activity (175 U/ml) was observed 5 h after induction. The lyophilized enzyme had a specific activity of 150 U/mg towards p-nitrophenyl acetate and 48 U/mg towards ethyl acetate. EstA was active in a wide range of pH (optimal 7.5) and temperature (optimal 44 degrees C) but became unstable above 50 degrees C. EstA exhibited modest enantioselectivity in the hydrolysis of alpha-phenylethyl acetate.