Xylanase from Aspergillus tamarii shows different kinetic parameters and substrate specificity in the presence of ferulic acid

Publication date: Available online 28 September 2018Source: Enzyme and Microbial TechnologyAuthor(s): Antonielle Viera Monclaro, Guilherme Lima Recalde, Francides Gomes da Silva Jr, Sonia Maria de Freitas, Edivaldo Ximenes Ferreira FilhoAbstractA 22 kDa xylanase (AtXyl1) from Aspergillus tamarii was purified by two chromatographic steps and presented preference for oat spelt (OSX), birchwood (BrX) and beechwood (BeX) xylans respectively, as substrates. AtXyl1 displays the highest activity at pH 5.5 and 55 °C and showed tolerance over a range of different phenolic compounds. The activity of AtXyl1 was not inhibited when the enzyme was incubated with ferulic acid (FA) using OSX or BrX as substrate. On the other hand, the incubation of AtXyl1 with BeX and FA resulted in an increase in enzyme activity. The molecular docking of a GH11 xylanase from Aspergillus niger with FA showed the preference for binding within the catalytic site. The position of FA was based on the presence or absence of a complexed substrate. When the enzyme from A. niger was docked in the absence of xylan in its crystal structure, FA interacted with Tyr164 and a water molecule. For the enzyme socked with xylo-oligosaccharides, FA interacted with Ser94, Tyr89 and the xylo-oligosaccharide present in the catalytic site. Thermodynamic parameters from the reaction of AtXyl1 with different xylans and FA indicate that FA can cause a conformational change in the enzyme, and this can influence the substrate fitt...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research