Four different polysaccharides (dextran, mannan, potassium pectate and sodium alginate) were used for derivatization of penicillin G acylase (PGA). The increase of specific activity of PGA in conjugates from 4 to 44% was observed. The conjugation of PGA with dextran and mannan extended its stability at extreme pH 3. These conjugates were 6-fold (DPGA-20) and 4.2-fold (MPGA) more stable than native PGA. Conjugates showed at pH 9 the increase of stability from 2.2-fold to 2.7-fold. The stability of PGA at higher temperature 55 degrees C was improved to value 107 min of the half-life time deactivation in case of dextran conjugate. Pectate-PGA conjugate demonstrated weak improvement of PGA stability at pH 9 and higher temperature. The stabilization effect of dextran and mannan in presence of organic solvents (n-butyl alcohol, n-propyl alcohol, methyl alcohol and butyl acetate) caused the increasing of half-time of deactivation from 1.3-fold to 10.6-fold in dependence of type of used polysaccharide and concentration of organic solvents. The conjugates of PGA with pectate and alginate did not show the perceptible improvement of stability of enzyme in the presence of organic solvents. (c) 2005 Elsevier Inc. All rights reserved.