Broad-specificity quinate (shikimate) dehydrogenasefrom Pinus taeda needles

Two proteins having quinate dehydrogenase (QDH, quinate:NAD(P)+-oxidoreductase, EC 1.1.1.24) and shikimate dehydrogenase (SDH, shikimate:NADP+-oxidoreductase, EC 1.1.1.25) activities were purified about 3 000-fold from young loblolly pine (Pinus taeda L.) needles. A combination of ammonium sulfate solubilization, and chromatographies on DEAE-cellulose, 2′, 5′ ADP-Sepharose and Mono-Q was used. Throughout all purification steps, the QDH activity consistently co-purified with the activity of the first of three forms of SDH, and the ratio of QDH/SDH was constant (variation from 1.63 to 1.89). These data indicate that both QDH and SDH activities are catalyzed by a single broad-specificity quinate (shikimate) dehydrogenase. Gel chromatography on Superdex 75 was used to estimate the native molecular mass of two forms of the enzyme as 35 and 53 kDa.