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.

Produksi β-Glukosidase Aspergillus niger BIO 2173 dengan Fermentasi Padat Menggunakan Substrat Dedak

“…Penyegaran kapang Aspergillus niger dilakukan dengan menumbuhkan kapang yang berasal dari media agar miring Potato Dextrose Agar (PDA). Kapang Aspergillus niger diinokulasikan pada tabung reaksi berisi media agar miring PDA steril secara aseptis, selanjutnya diinkubasi pada suhu 28 o C selama 5 hari (Ahmed et al, 2015).…”

“…Isolasi β-glukosidase dari kapang dilakukan baik dengan menggunakan metode fermentasi media padat maupun fermentasi media cair (Singhania et al, 2013). Berbagai jenis kapang telah dijadikan sebagai sumber β-glukosidase seperti Aspergillus niger (Raza et al, 2011;Zahoor et al, 2011;Qian et al, 2012;Junior et al, 2014;Ahmed et al, 2015Julia et al, 2016, Aspergillus terreus (Elshafei et al, 2011), Aspergillus fumigatus (Liu et al, 2012), Fusarium proliferatum (Gao et al, 2012), Penicillium pinophilum (Joo et al, 2010), Penicillium italicum (Park et al, 2012), Trichoderma viride (Irshad et al, 2013), dan Trichoderma reesei (Zheng et al, 2017).…”

Methylation of position 8 in the pyridine moiety of the N-(benzyl)-2-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamide molecule as an attempt to enhance their analgesic properties

“…This methodology has long been successfully used by medicinal chemists to intensify the specific action [2,3], increase selectivity towards a particular receptor [4][5][6], improve the thermal stability [7], biocompatibility [8], bioavailability [9], safety [10], correction of taste [11], as well as to solve many other problems [11][12][13][14][15] associated with optimization of both the known and newly developed drugs.…”