title: Chemical modification of Aspergillus niger β-glucosidase and its catalytic properties.
abstract: Aspergillus niger β-glucosidase was modified by covalent coupling to periodate activated polysaccharides (glycosylation). The conjugated enzyme to activated starch showed the highest specific activity (128.5 U/mg protein). Compared to the native enzyme, the conjugated form exhibited: a higher optimal reaction temperature, a lower Ea (activation energy), a higher K m (Michaelis constant) and Vmax (maximal reaction rate), and improved thermal stability. The calculated t 1/2 (half-life) values of heat in-activation at 60 °C and 70 °C were 245.7 and 54.5 min respectively, whereas at these temperatures the native enzyme was less stable (t 1/2 of 200.0 and 49.5 min respectively). The conjugated enzyme retained 32.3 and 29.7%, respectively from its initial activity in presence of 5 mM Sodium Dodecyl Sulphate (SDS) and p -Chloro Mercuri Benzoate ( p -CMB), while the native enzyme showed a remarkable loss of activity (retained activity 1.61 and 13.7%, respectively). The present work has established the potential of glycosylation to enhance the catalytic properties of β-glucosidase enzyme, making this enzyme potentially feasible for biotechnological applications.
authors.affiliation: Department of Chemistry of Natural and Microbial Products, National Research Centre, Cairo, Egypt.
authors.forename: Samia A
authors.initials: SA
authors.lastname: Ahmed
authors.affiliation: Department of Chemistry of Natural and Microbial Products, National Research Centre, Cairo, Egypt.
authors.forename: Nefisa M A
authors.initials: NM
authors.lastname: El-Shayeb
authors.affiliation: Microbiology and Immunology Faculty of Pharmacy, Cairo University, Cairo, Egypt.
authors.forename: Abdel-Gawad M
authors.initials: AG
authors.lastname: Hashem
authors.affiliation: Department of Chemistry of Natural and Microbial Products, National Research Centre, Cairo, Egypt.
authors.forename: Shireen A A
authors.initials: SA
authors.lastname: Saleh
authors.affiliation: Department of Chemistry of Natural and Microbial Products, National Research Centre, Cairo, Egypt.
authors.forename: Ahmed F
authors.initials: AF
authors.lastname: Abdel-Fattah
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D006031:Glycosylation; D007700:Kinetics; D013696:Temperature; D001617:beta-Glucosidase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D001617:beta-Glucosidase
keywords: enzyme stability; glycosylation; soluble polysaccharides; β-glucosidases