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

Research output: Contribution to journalArticleResearchpeer-review

35 Citations (Scopus)

Abstract

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
Volume1435
Issue number1-2
DOIs
Publication statusPublished - 16 Nov 1999
Externally publishedYes

Keywords

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

Cite this