Purification of cytosolic β-glucosidase from pig liver and its reactivity towards flavonoid glycosides

Nigel Lambert, Paul A. Kroon, Craig B. Faulds, Geoff W. Plumb, W. Russell McLauchlan, Andrea J. Day, Gary Williamson

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37 Citations (Scopus)


Flavonoid glycosides are common dietary components which may have health-promoting activities. The metabolism of these compounds is thought to influence their bioactivity and uptake from the small intestine. It has been suggested that the enzyme cytosolic β-glucosidase could deglycosylate certain flavonoid glycosides. To test this hypothesis, the enzyme was purified to homogeneity from pig liver for the first time. It was found to have a molecular weight (55 kDa) and specific activity (with p-nitrophenol glucoside) consistent with other mammalian cytosolic β-glucosidases. The pure enzyme was indeed found to deglycosylate various flavonoid glycosides. Genistein 7-glucoside, daidzein 7-glucoside, apigenin 7-glucoside and naringenin 7-glucoside all acted as substrates, but we were unable to detect activity with naringenin 7-rhamnoglucoside. Quercetin 4'-glucoside was a substrate, but neither quercetin 3,4'-diglucoside, quercetin 3-glucoside nor quercetin 3-rhamnoglucoside were deglycosylated. Estimates of K(m) ranged from 25 to 90 μM while those for V(max) were about 10% of that found with the standard artificial substrate p-nitrophenol glucoside. The non-substrate quercetin 3-glucoside was found to partially inhibit deglycosylation of quercetin 4'-glucoside, but it had no effect upon activity with p-nitrophenol glucoside. This study confirms that mammalian cytosolic β-glucosidase can deglycosylate some, but not all, common dietary flavonoid glycosides. This enzyme may, therefore, be important in the metabolism of these compounds.

Original languageEnglish
Pages (from-to)110-116
Number of pages7
JournalBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
Issue number1-2
Publication statusPublished - 16 Nov 1999
Externally publishedYes


  • β-Glucosidase
  • Cytosolic
  • Flavonoid
  • Glucoside
  • Mammalian

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