Characterisation of a recombinant β-xylosidase (xylA) from Aspergillus oryzae expressed in Pichia pastoris

Kirikyali, Narin; Wood, Jonathan; Connerton, Ian F.

Abstract

β-xylosidases catalyse the hydrolysis of short chain xylooligosaccharides from their non-reducing ends into xylose. In this study we report the heterologous expression of Aspergillus oryzae β-xylosidase (XylA) in Pichia pastoris under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter. The recombinant enzyme was optimally active at 55°C and pH 4.5 with Km and Vmax values of 1.0 mM and 250 μmol min−1 mg−1 respectively against 4-nitrophenyl β-xylopyranoside. Xylose was a competitive inhibitor with a Ki of 2.72 mM, whereas fructose was an uncompetitive inhibitor reducing substrate binding affinity (Km) and conversion efficiency (Vmax). The enzyme was characterised to be an exo-cutting enzyme releasing xylose from the non-reducing ends of β-1,4 linked xylooligosaccharides (X2, X3 and X4). Catalytic conversion of X2, X3 and X4 decreased (Vmax and kcat) with increasing chain length.

Citation

Kirikyali, N., Wood, J., & Connerton, I. F. (2014). Characterisation of a recombinant β-xylosidase (xylA) from Aspergillus oryzae expressed in Pichia pastoris. AMB Express, 4(68), https://doi.org/10.1186/s13568-014-0068-1

• Journal Article Type: Article
• Publication Date: Aug 31, 2014
• Deposit Date: May 22, 2015
• Publicly Available Date: May 22, 2015
• Journal: AMB Express
• Electronic ISSN: 2191-0855
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 68
• DOI: https://doi.org/10.1186/s13568-014-0068-1
• Public URL: https://nottingham-repository.worktribe.com/output/733589
• Publisher URL: http://www.amb-express.com/content/4/1/68