A new lipase from porcine pancreas was adsorbed on PEI-coated support and utilized in the resolution of (+/-)-glycidyl butyrate, reaching a moderate E value of 6. The treatment of the adsorbed lipase with glutaraldehyde permitted to increase this value by a 10-fold factor (to E = 61). Similar improvement of enantioselectivity promoted by the glutaraldehyde treatment was obtained employing immobilized preparations of other lipases. Moreover, enzyme activity in some instances can be even improved by this treatment, and the effect of the experimental conditions on the enzyme activity was completely altered. Thus, this simple treatment, in many cases necessary to stabilize the enzyme preparations, may be also a powerful tool to alter the enzyme properties. (c) 2006 Elsevier Inc. All rights reserved.