Purification of pantoate and dimethylmalate dehydrogenase from Pseudomonas fluorescens UK-1.

Pantoate dehydrogenase and dimethylmalate dehydrogenase were purified 69- and 112-fold, respectively, from Pseudomonas fluorescens UK-1 by ammonimu sulphate precipitation. Ultrogel AcA 34 gel filtration, hydroxyapatite column chromatography, heat treatment and Ultrogel AcA 44 gel filtration. The enzymes were evaluated for homogeneity (pantoate dehydrogenase was estimated to be about 95% pure) by disc and sodium dodecyl sulphate gel electrophoresis and by immunodiffusion. Pantoate and dimethylmalate dehydrogenases have molecular weights of 83 000 and 138 000, respectively, and are dissociable into four identical subunits with molecular weights of 24 000 and 34 000.