A Very Stable β-Glucosidase from a Candida molischiana Mutant Strain : Enzymatic Properties, Sequencing, and Homology with Other Yeast β-Glucosidases

Abstract

We purified a β-glucosidase from the mutant strain Candida molischiana 35M5N. Analysis of the kinetic properties of this enzyme did not show any differences between the previously purified wild-type enzyme and that of the mutant. Nevertheless, a study of the stability of the enzyme at different pH levels and temperatures showed the increased resistance of this protein. This enzyme was found to be stable at pH 5 for 145 h and retained 78% of its initial activity after the same time at pH 3.5 (optimal pH) and 30°C. This difference between the wild-type and the mutant enzyme could be explained by differences in the quantity or quality of glycosylation. This glycoprotein showed different forms after deglycosylation. Some peptides from this protein were also sequenced. An homology analysis found similarities between this β-glucosidase and β-glucosidases of Candida pelliculosa and Schizophyllum commune.