The Metabolism of Quinate in Pea Roots (Purification and Partial Characterization of a Quinate Hydrolyase)

Abstract

QA and SK are compounds that often occur in relatively high concentrations in green and nongreen tissues of herbaceous (Yoshida et al., 1975) and woody angiosperms (Boudet, 1973). For example, in the spring, high amounts of QA are formed in developing coniferous needles (2-10% of dry weight) in the course of photosynthetic C02 fixation (Dittrich and Kandler, 1971). This QA pool is metabolized during the lignification process in the summer. QA is also a precursor for chlorogenic acids and is converted into other secondary products like protocatechuic acid (Haslam, 1974). Although QA is formed by a QA:NAD(P)+ oxidoreductase from DHQ, an intermediate in the SK pathway (Bentley, 1990), its involvement in AAA biosynthesis is not clear. 14C-labeled QA is incorporated into free and proteinbound AAA in different herbaceous species and members of the Rosaceae (Weinstein et al., 1959(Weinstein et al., , 1961 and in mung bean (Minamikawa et al., 1969). However, the actual enzymatic steps for channeling QA into the SK pathway are not known.In pea (Pisum sativum L.) epicotyls, an irreversible conversion of QA into SK has been found (Tazaki et al., 1974), whereas the reaction appears to be reversible in mung bean (Minamikawa et al

Annual changes in the concentration of minerals and organic compounds of Quercus suber leaves

“…This acid can attain relatively high concentrations in angiosperms (Boudet 1973, Yoshida et al 1975, but its precise metabolic functions in higher plants have not been elucidated. In the gymnosperm Picea abies, quinic acid is intensively produced in the needles in spring and metabolized in summer, apparently participating in lignification processes (Dittrich and Kandler 1971 in Leuschner et al 1995). The presence of quinic acid in Q. suber has already been reported (Boudet 1973), but our results show a pattern of distribution during the year quite distinct from that described for Q. robur (Peltier et al 1998).…”

“…Therefore, malate does not seem to be important for Q. suber under drought and the predominant acid is quinic acid, which is one of the early intermediates of the shikimate pathway. It is formed in the chloroplast from dehydroquinate by the action of quinate dehydrogenase (Gamborg 1967, Leuschner et al 1995 and also from shikimate by quinate hydrolyase (Leuschner et al 1995, Herrmann andWeaver 1999). This acid can attain relatively high concentrations in angiosperms (Boudet 1973, Yoshida et al 1975, but its precise metabolic functions in higher plants have not been elucidated.…”

Sugar and Organic Acid Composition in the Fruit Juice of Different Actinidia Varieties

“…Although the physiological and nutritional importance of quinic acid has not been established, it has attracted great interest. Quinic acid putatively serves as a precursor for the biosynthesis of polyphenols, such as chlorogenic acids and flavonoids, in plants (Weinstein et al, 1961;Leuschner et al, 1995). These dietary polyphenols act as a radical trapping antioxidant, which are widely perceived as contributing to prevention of various degenerative diseases including cardiovascular diseases and cancers (Scalbert et al, 2005).…”

Molecular Characterization of Quinate and Shikimate Metabolism in Populus trichocarpa

“…Absence of QD Activity-Quinate can be taken up by intact leucoplasts from pea roots and converted directly into shikimate via a QD activity (also referred to as quinate hydrolyase) (42,64,65). Because of the similarity of the QD reaction mechanism with that of DQD, we originally hypothesized that QD may be encoded by DQD-like genes in poplar.…”

“…Enzymes involved are either quinate dehydratase (QD; also referred to as quinate hydrolyase; no EC number assigned) or quinate dehydrogenase (QDH; EC 1.1.1.24) (11). QDHs have been (partially) purified and characterized in several angiosperms and gymnosperms (30, 34 -41), but QD has been partially characterized only in pea (42). However, genes encoding these two enzymes have not been identified to date.…”