Candida rugosa lipase coated with glutamic acid didodecyl ester ribitol amide was used for the catalysis of hydrolytic reactions in an organic-aqueous two-phase system using the hydrolysis of olive oil as a model reaction. The optimal reaction conditions of the coated lipase were similar to those of the native lipase, but the coated lipase showed a higher activity. The maximum activity of the coated lipase reached 48.8 mmol acids min(-1) g(-1) protein, 1.8 times higher than that of the native lipase. The half-lives of the coated lipase in iso-octane and the native lipase in phosphate buffer at 30 degreesC were around 9 and 12 h, and the final residual activities were 25 and 19% of their initial values, respectively. The coated lipase exhibited a substrate specificity similar to that of the native lipase and olive oil was the most suitable substrate among the esters tested. The Michaelis constant (K,) of the coated lipase was only half that of the native lipase while the maximum velocity (v(max)) was 1.4 times higher. (C) 2003 Elsevier Science Ltd. All rights reserved.