Bacterial cis-dihydrodiol dehydrogenases: comparison of physicochemical and immunological protperties

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Abstract
Cells of Pseudomonas putida NP, Pseudomonas sp. (NCIB 9816) and a Nocardia sp., after growth on naphthalene as sole source of Ca and energy, contain a NAD+-dependent enzyme that oxidizes cis-dihydrodiols of mono- and polycyclic aromatic compounds. Cells of a strain of P. putida biotype A, when grown either on toluene or benzene vapors, contained a dehydrogenase that oxidized dihydrodiols of aromatic hydrocarbons with cis stereochemistry and required NAD+ as an electron acceptor. In all these cases, no enzymatic activity was detected when trans-naphthalene dihydrodiol was used as a substrate. Purified cis-naphthalene dihydrodiol dehydrogenase was injected into rabbits to obtain antibodies. Physicochemical and immunological properties of cis-dihydrodiol:NAD+ oxidoreductases from 4 different organisms were examined. Kinetic analysis showed that, in all the cases, enzymes exhibited higher affinity for cis-dihydrodiols than for NAD+ and had pH optima between 8.8-9.0, except in the case of the enzyme from Nocardia sp., which showed maximum activity at pH 8.4. Molecular-weight determination of the dehydrogenases from the 4 different organisms by gel filtration on a Sephadex G-200 column gave values ranging from 92,000 for the enzyme from Nocardia sp. to 160,000 for that from P. putida biotype A. All the dehydrogenases, except the one from Nocardia sp., exhibited immunological cross-reaction with the antibodies prepared against the enzyme purified from P. putida NP.

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