| The grapefruit plant, Citrus paradisi, tends to accumulate high levels of flavonoid glycosides such as flavanones and flavones. Flavonoids have a vast array of important functions in plants and also in humans. Glucosyltransferases (GTs) are enzymes responsible for glucosylation reactions. In our pursuit to study the structure and function of flavonoid GTs, we have used molecular approaches to identify, clone, express, and functionally characterize the enzymes. This research was designed to test the hypothesis that PGT3 is a flavonoid glucosyltransferase and is subject to biochemical regulation. PGT3 has been tested for GT activity with compounds representing subclasses of flavonoids as well as some simple phenolics. Results indicate GT activity with 6 substrates, p-hydroxybenzoic acid, vanillin, vanillic acid, p-hydroxyphenylpyruvate, gentisic acid, and catechol. A second project designed to clone putative PGT8 into the Pichia expression system has been completed. |
