HYDROAROMATIC METABOLISM IN RHODOCOCCUS-RHODOCHROUS - PURIFICATION AND CHARACTERIZATION OF ITS NAD-DEPENDENT QUINATE DEHYDROGENASE

Quinate grown cells of Rhodococcus rhodochrous N75 metabolized both quinate and shikimate via protocatechuate to succinate and acetyl CoA. The initial enzyme of the hydroaromatic pathway, quinate dehydrogenase was purified 188-fold to electrophoretic homogeneity. The enzyme is a monomer with a native relative molecular mass of 44,000 and is NAD-dependent. The enzyme is highly stereospecific with regard to hydroaromatic substrates, oxidising only the axial hydroxyl group at C-3 of (-)-isomers of quinate, shikimate, dihydroshikimate and t-3, t-4-dihydroxycyclohexane-c-1-carboxylate, but shows activity with several NAD analogues. © 1990 Springer-Verlag.