EFFECT OF SURFACTANTS ON ACTIVITY AND STABILITY OF NATIVE AND CHEMICALLY-MODIFIED LIPASE-A AND LIPASE-B FROM CANDIDA-RUGOSA

The effect of sodium dodecyl sulfate (SDS) and Triton X-100 on the hyd rolytic activity of lipases A and B from Candida rugosa has been studi ed. Lipase B is significantly more affected than lipase A by the prese nce of both surfactants; Triton X-100 produces a more deleterious effe ct than SDS with both isoenzymes. In addition, the stability of lipase s A and B in the presence of different concentrations of SDS was inves tigated; lipase A was more stable than isoform B. Both isoenzymes were chemically modified by reaction of their amino groups with octanoyl c hloride or activated polyethylene glycol (PEG, mel. wt. 5000). In all cases the modification produced a protective effect against denaturati on by SDS. In particular, PEG(5000)-lipases A and B were significantly more stable (stabilization factor: 3-4) than the native enzymes at th e surfactant concentrations tested.