Homogenates of yeast cultures with engineered catalases F148V and V111A reveal higher specific activities after incubation at permissive temperature.

Certain mutant proteins produced by site-directed mutagenesis of corresponding genes exhibit markedly altered enzymic activity which can have influence on the growth of cultures harboring such a construct. Engineered yeast peroxisomal catalases F148V and V111A show increased specific activities if isolated from cultures grown at 22 degrees C (in comparison to standard 30 degrees C). This effect is opposite to that found in the wild type catalase A. The possible reason could be the decreased interaction of mutated (and possibly misfolded) proteins with heat shock proteins at the permissive temperature. From the kinetic and spectral results we conclude that the single residue mutant F148V is less stable than the mutant V111A.