Plant Physiol. Journal of Pharmacology and Experimental Therapeutics
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Plant Physiology 95:1254-1258 (1991)
© 1991 American Society of Plant Biologists

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Metabolism and Enzymology

Partial Purification and Some Properties of Flavonol 7-Sulfotransferase from Flaveria bidentis1

Luc Varin and Ragai K. Ibrahim

Plant Biochemistry Laboratory, Department of Biology Concordia University, Montreal, Quebec, Canada H3G 1M8

A novel flavonol-specific sulfotransferase was partially purified from the shoot tips of Flaveria bidentis var. Angustifolia O.K. (Asteraceae) by chromatography on 3'-phosphoadenosine 5'-phosphate-agarose affinity column and chromatofocusing on Mono P. The latter step resulted in the separation of two isoforms, both of which exhibited expressed specificity for position 7 of quercetin 3,3'- and quercetin 3,4'-disulfate. The 7-sulfotransferase isoforms I and II had a pH optimum of 7.5 in phosphate buffer, apparent pl values of 6.5 and 6.3, and an Mr of 35,000. They had no requirement for divalent cations and were not inhibited by EDTA or SH group reagents. Their Km values for both the sulfate donor and flavonol acceptor were of the same order of magnitude (0.20-0.46 micromolar). This enzyme, together with the recently reported flavonol 3-, 3'-, and 4'-sulfotransferases from F. chloraefolia (L Varin, RK Ibrahim [1989] Plant Physiol 90: 977-981) form the complement involved in the biosynthesis of polysulfated flavonols in this genus. A proposed sequential order for the enzymatic sulfation in both species is described.

1 This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Department of Higher Education, Government of Quebec. L. V. was the recipient of an NSERC postgraduate scholarship, a Concordia University Fellowship, and an NSERC postdoctoral Fellowship.




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L. Varin, F.édér. Marsolais, and N. Brisson
Chimeric Flavonol Sulfotransferases Define a Domain Responsible for Substrate and Position Specificities
J. Biol. Chem., May 26, 1995; 270(21): 12498 - 12502.
[Abstract] [Full Text] [PDF]


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Copyright © 1991 by the American Society of Plant Biologists