Functional expression of human liver cytosolic β-glucosidase in Pichia pastoris: Insights into its role in the metabolism of dietary glucosides

Jean Guy Berrin, W. Russell McLauchlan, Paul Needs, Gary Williamson, Antoine Puigserver, Paul A. Kroon, Nathalie Juge

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Human tissues such as liver, small intestine, spleen and kidney contain a cytosolic β-glucosidase (CBG) that hydrolyses various β-D-glycosides, but whose physiological function is not known. Here, we describe the first heterologous expression of human CBG, a system that facilitated a detailed assessment of the enzyme specificity towards dietary glycosides. A full-length CBG cDNA (cbg-1) was cloned from a human liver cDNA library and expressed in the methylotrophic yeast Pichia pastoris at a secretion yield of ≈ 10 mg·L-1. The recombinant CBG (reCBG) was purified from the supernatant using a single chromatography step and was shown to be similar to the native enzyme isolated from human liver in terms of physical properties and specific activity towards 4-nitrophenyl-β-D-glucoside. Furthermore, the reCBG displayed a broad specificity with respect to the glycone moiety of various aryl-glycosides (β-D-fucosides, α-L-arabinosides, β-D-glucosides,β-D-galactosides,β-L-xylosides,β-D- arabinosides), similar to the native enzyme. For the first time, we show that the human enzyme has significant activity towards many common dietary xenobiotics including glycosides of phytoestrogens, flavonoids, simple phenolics and cyanogens with higher apparent affinities (Km) and specificities (kcat/Km) for dietary xenobiotics than for other aryl-glycosides. These data indicate that human CBG hydrolyses a broad range of dietary glucosides and may play a critical role in xenobiotic metabolism.

Original languageEnglish
Pages (from-to)249-258
Number of pages10
JournalEuropean Journal of Biochemistry
Issue number1
Publication statusPublished - 9 Feb 2002
Externally publishedYes


  • First-pass metabolism
  • Flavonoids
  • Heterologous expression
  • Isoflavones
  • Xenobiotic metabolism

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