Applied Microbiology and Biotechnology

, Volume 89, Issue 3, pp 685–696

Purification of exo-1,3-beta-glucanase, a new extracellular glucanolytic enzyme from Talaromyces emersonii

Authors

  • Elaine O’Connell
    • Molecular Glycobiotechnology Group, Biochemistry, School of Natural SciencesNational University of Ireland
  • Charles Piggott
    • Department of Life SciencesUniversity of Limerick
    • Molecular Glycobiotechnology Group, Biochemistry, School of Natural SciencesNational University of Ireland
Biotechnologically Relevant Enzymes and Proteins

DOI: 10.1007/s00253-010-2883-x

Cite this article as:
O’Connell, E., Piggott, C. & Tuohy, M. Appl Microbiol Biotechnol (2011) 89: 685. doi:10.1007/s00253-010-2883-x

Abstract

The moderately thermophilic aerobic ascomycete Talaromyces emersonii secretes, under selected growth conditions, several β-glucan hydrolases including an exo-1,3-β-glucanase. This enzyme was purified to apparent homogeneity in order to characterise its biochemical properties and investigate hydrolysis of different β-glucans, including laminaran, a 1,3-β-glucan from brown algae. The native enzyme is monomeric with a molecular mass of ~40 kDa and a pI value of 4.3, and is active over broad ranges of pH and temperature, with optimum activity observed at pH 5.4 and 65 °C. At pH 5.0, the enzyme displays strict specificity for laminaran (apparent Km 1.66 mg mL−1; Vmax 7.69 IU mL−1) and laminari-oligosaccharides and did not yield activity against 1,4-β-glucans, 1,3;1,4-β-glucans or 4-nitrophenyl- and methylumbelliferyl-β-d-glucopyranosides. Analysis of hydrolysis products formed during time-course hydrolysis of laminaran by high-performance anion exchange chromatography with pulsed amperometric detection revealed a strict exo mode of action, with glucose being the sole reaction product even at the initial stages of hydrolysis. The T. emersonii exo-1,3-β-glucanase was inhibited by glucono-δ-lactone (Ki 1.25 mM) but at significantly higher concentrations than typically inhibitory for exo-glycosidases such as β-glucosidase. ‘De novo’ sequence analysis of the purified enzyme suggests that it belongs to family GH5 of the glycosyl hydrolase superfamily. The results clearly show that the exo-1,3-β-glucanase is yet another novel enzyme present in the β-glucanolytic enzyme system of T. emersonii.

Keywords

Exo-1,3-β-glucanaseLaminaranTalaromyces emersoniiGlucono-δ-lactonePurification

Copyright information

© Springer-Verlag 2010