Broad-specificity quinate (shikimate) dehydrogenase from Pinus taeda needles

Two proteins having quinate dehydrogenase (QDH, quinate:NAD(P)(+)-oxidoredu ctase, EC 1.1.1.24) and shikimate dehydrogenase (SDH, shikimate:NADP(+)-oxi doreductase, EC 1.1.1.25) activities were purified about 3000-fold from you ng loblolly pine (Pinus taeda L.) needles. A combination of ammonium sulfat e solubilization, and chromatographies on DEAE-cellulose, 2', 5' ADP-Sephar ose and Mono-Q was used. Throughout all purification steps, the QDH activit y 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 sin gle 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. (C) 2000 Editions scientifiques et medical es Elsevier SAS.