Tag Archives: Penicillium canescens

Influence of chemical reagents and UV irradiation on the activity of Penicillium canescens α-galactosidase

N. V. Borzova, L. D. Varbanets

Danylo Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv;
е-mail: nv_borzova@bigmir.net

Investigations of the influence of chemical and physical factors on the conformational and functional properties of enzymes make a significant contribution to the study of the mechanism of action of industrially important proteins. The aim of the work was to evaluate the effect of chemical reagents and UV irradiation on the catalytic properties of Penicillium canescens α-galactosidase. Enzyme activity was assessed with p-nitrophenyl-α-D-galactopyranoside. Studies of the functionally active glycosidase groups were carried out on the basis of inhibitory and kinetic analysis using Dixon and Luinuiver-Burke methods with help of specific chemical reagents. A significant decrease in the activity of α-galactosidase in the presence of carbodiimi­des, diethylpyrocarbonate, the reagents on sulfhydryl groups was shown. A UV-induced decrease in enzyme activi­ty in the dose range of 900-7200 J/m2 was noted. Based on the data obtained, the imidazole group of histidine, carboxyl groups of C-terminal amino acids and the SH-groups of cysteine are assumed to play an important role in the manifestation of the activity of P. canescens α-galactosidase.

Role of glycosylation in secretion and stability of micromycetes α-galactosidase

N. V. Borzova, O. V. Gudzenko, L. D. Varbanets

Zabolotny Institute of Microbiology and Virology,
National Academy of Sciences of Ukraine, Kyiv;
e-mail: nv_borzova@bigmir.net

The effect of the glycosylation inhibitors (tunicamycin and 2-deoxy-D-glucose) on the activity, stabili­ty and production of fungal glycosidases has been studied. It was shown that inhibition of N-glycosylation sites did not affect the secretion of Aspergillus niger α-galactosidase, however reduced yield of Cladosporium cladosporioides and Penicillium canescens α-galactosidases. Changes in the level of O-glycosylation resulted in a significant reduction in the activity and stability of α-galactosidases of all three producers tested. Activity of the modified enzymes was significantly lower than that of the native ones, and was  2.6 and 0.33 U/mg for A. niger α-galactosidase, 3.3 and 32.5 U/mg for C. cladosporioides α-galactosidase, 11.66 and 31.1 U/mg for P. canescens α-galactosidase, respectively. A. niger α-galactosidase completely lost activity during purification and storage. The decrease of thermal stability at 55 °C by 20% was shown for C. cladosporioides and P. canescens α-galactosidases. It was also noted that O-deglycosylation led to a decrease in resistance of these enzymes to the action of proteases.