Kinetic mechanism of a flavonol-ring-B O-glucosyltransferase from Chrysosplenium americanum.
The kinetic mechanism of a flavonol-ring-B O-glucosyltransferase from Chrysosplenium americanum was investigated. Substrate interaction kinetics for the flavonol and UDPG gave converging lines, which were consistent with a sequential bireactant binding mechanism. They also showed substrate inhibition with respect to the flavonol. Intercept and slope replots were linear and gave a KA of 250 microM and a KB of 10 microM. Product-inhibition studies showed competitive inhibition between UDPG and UDP (KiQ 20 microM) and non-competitive inhibition between the flavonol substrate and its glucoside (KiP 1 mM). Kinetic patterns were consistent with an ordered bi-bi mechanism, where UDPG is the first substrate to bind to the enzyme and UDP is the final product released. The high KiP value, as compared with that of KB, indicates that the reaction is not inhibited by the glucosylated products formed and conforms with the accumulation of flavonol glucosides in C. americanum.[1]References
- Kinetic mechanism of a flavonol-ring-B O-glucosyltransferase from Chrysosplenium americanum. Khouri, H., Ibrahim, R.K. Eur. J. Biochem. (1984) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
