Journal ArticleDOI
First bacterial chalcone isomerase isolated from Eubacterium ramulus
TLDR
The human fecal anaerobe Eubacterium ramulus is capable of degrading various flavonoids, including the flavone naringenin, and the first report on a bacterial chalcone isomerase is reported, which catalyzed the isomerization of naringein chal cone, isoliquiritigenin and butein, three chalcones that differ in their hydroxylation pattern.Abstract:
The human fecal anaerobe Eubacterium ramulus is capable of degrading various flavonoids, including the flavone naringenin. The first step in the proposed degradation pathway is the isomerization of naringenin to the corresponding chalcone. Cell-free extracts of E. ramulus displayed chalcone isomerase activity. The enzyme from E. ramulus was purified to homogeneity. Its apparent molecular mass was estimated to be 136 and 129 kDa according to gel filtration and native polyacrylamide gel electrophoresis, respectively. Chalcone isomerase is composed of one type of subunit of 30 kDa. The purified enzyme catalyzed the isomerization of naringenin chalcone, isoliquiritigenin, and butein, three chalcones that differ in their hydroxylation pattern. N-bromosuccinimide, but also naringenin and phloretin, inhibited the purified enzyme considerably. This is the first report on a bacterial chalcone isomerase. The physiological function of the purified enzyme is unclear, but an involvement in the conversion of the flavanone naringenin to the chalcone is proposed.read more
Citations
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References
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Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4
TL;DR: Using an improved method of gel electrophoresis, many hitherto unknown proteins have been found in bacteriophage T4 and some of these have been identified with specific gene products.
Journal ArticleDOI
The Determination of Enzyme Dissociation Constants
Hans Lineweaver,Dean Burk +1 more
TL;DR: On the basis of the assumed theory the rate of the observed reaction is directly proportional to the concentration of the enzyme-substrate compound, where (E:l = (ES).
Journal ArticleDOI
DIETARY FLAVONOIDS: Bioavailability, Metabolic Effects, and Safety
Julie A. Ross,Christine M. Kasum +1 more
TL;DR: Investigation in the possible health benefits of flavonoids has increased owing to their potent antioxidant and free-radical scavenging activities observed in vitro, and there is growing evidence from human feeding studies that the absorption and bioavailability of specific flavonoid is much higher than originally believed.
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Plasma Kinetics and Urinary Excretion of the Flavanones Naringenin and Hesperetin in Humans after Ingestion of Orange Juice and Grapefruit Juice
TL;DR: It is concluded that because of the relatively high concentrations of flavanones in plasma after ingestion of orange juice or grapefruit juice, considerable health effects could ensue in individuals consuming them regularly.
Journal ArticleDOI
Flavanones, chalcones and dihydrochalcones – nature, occurrence and dietary burden
TL;DR: In this paper, the occurrence in foods of flavanones, chalcones and dihydrochalcones is reviewed. But no data for plasma or tissue levels, but both endogenous and gut flora metabolites of both classes of compound are found in urine.