Comparative aspects of some bacterial dehydrogenases and transhydrogenases.

Ragland, T. E. (Brandeis University, Waltham, Mass.), T. Kawasaki, and J. M. Lowenstein. Comparative aspects of some bacterial dehydrogenases and transhydrogenases. J. Bacteriol. 91:236-244. 1966.-Twenty-eight diverse bacterial species were surveyed for the activities and coenzyme specificities of four enzymes: isocitrate dehydrogenase (ICDH), glucose-6-phosphate dehydrogenase (G-6-PDH), 6-phosphogluconate dehydrogenase (6-PGDH), and reduced nicotinamide adenine dinucleotide phosphate-nicotinamide adenine dinucleotide (NAD) transhydrogenase (TH). Most of the species that exhibited a nicotinamide adenine dinucleotide phosphate (NADP)-linked ICDH also showed significant TH activity, but there were several which did not. Only one of the organisms tested, Xanthomonas pruni, had an ICDH active with both NAD and NADP; it was devoid of TH activity. Acetobacter suboxydans, which lacks ICDH altogether, also had no TH. Some of the species examined had G-6-PDH or 6-PGDH (or both) of dual coenzyme specificity, but there was no apparent relation between these findings and the presence or absence of TH. The TH reaction was assayed by use of analogues of NAD as acceptors. The bacteria could be divided into two groups on the basis of TH specificity, one group reacting at a much faster rate with the 3-acetylpyridine analogue of NAD than with the thionicotinamide analogue, whereas the converse was true for the other group. A few organisms showed no marked specificity for either analogue. This division of specificity can be related to the currently accepted taxonomic classification of the organisms, although a few apparent anomalies were found.