Effect of glycosylation on the biochemical properties of beta-xylosidases from Aspergillus versicolor.
Aspergillus versicolor grown on xylan or xylose produces two beta-xylosidases with differences in biochemical properties and degree of glycosylation. We investigated the alterations in the biochemical properties of these beta-xylosidases after deglycosylation with Endo-H or PNGase F. After deglycosylation, both enzymes migrated faster in PAGE or SDS-PAGE exhibiting the same R(f). Temperature optimum of xylan-induced and xylose-induced beta-xylosidases was 45 degrees C and 40 degrees C, respectively, and 35 degrees C after deglycosylation. The xylan-induced enzyme was more active at acidic pH. After deglycosylation, both enzymes had the same pH optimum of 6.0. Thermal resistance at 55 degrees C showed half-life of 15 min and 9 min for xylose- and xylan-induced enzymes, respectively. After deglycosylation, both enzymes exhibited half-lives of 7.5 min. Native enzymes exhibited different responses to ions, while deglycosylated enzymes exhibited identical responses. Limited proteolysis yielded similar polypeptide profiles for the deglycosylated enzymes, suggesting a common polypeptide core with differential glycosylation apparently responsible for their biochemical and biophysical differences.
Somera
Alexandre Favarin
AF
Departamentos de Biologia e Química, Universidade de São Paulo, Avenida Bandeirantes 3900, CEP 14040-901, Ribeirão Preto, SP, Brasil.
Pereira
Marita Gimenez
MG
Souza Guimarães
Luis Henrique
LH
Polizeli
Maria de Lourdes Teixeira de Moraes
Mde L
Terenzi
Héctor Francisco
HF
Melo Furriel
Rosa Prazeres
RP
Jorge
João Atílio
JA
D001230:Aspergillus / Q000201:enzymology*; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D011499:Protein Processing, Post-Translational; D013696:Temperature; D014995:Xylosidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D005656:Fungal Proteins; D006023:Glycoproteins; D014995:Xylosidases