Chemical modification of Aspergillus niger B-glucosidase and its catalytic properties
Ahmed, Samia A; El-Shayeb, Nefisa MA; Hashem, Abdel-Gawad M; Saleh, Shireen AA; Abdel-Fattah, Ahmed F.
Braz. J. Microbiol.;
46(1): 23-28, Jan.- Mar. 2015. graf
Artigo
em Inglês
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| ID: vti-481373
Resumo
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 Km (Michaelis constant) and Vmax (maximal reaction rate), and improved thermal stability. The calculated t1/2 (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 (t1/2 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.(AU)
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