Studies on a gram-positive hydrogen bacterium, Nocardia opaca strain 1b

✍ Scribed by Probst, Irmelin ;Schlegel, H. G.

• Book ID: 104762420
• Publisher: Springer-Verlag
• Year: 1973
• Weight: 706 KB
• Volume: 88
• Category: Article
• ISSN: 0003-9276
• DOI: 10.1007/bf00409943

✦ Synopsis

In Nocardia opaca strain lb the key enzymes of the Entner-Doudoroff pathway, 6-phosphogluconate dehydrase and 2-kcto-3-deoxy-6-phosphogluconate aldolase, are inducible, while glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase are constitutively formed. In autotrophically grown cells the fructose diphosphate aldolase has six-fold specific activity compared to fructose-or glueonate-grown cells. Molecular hydrogen represses the adaptation to fructose, glucose, or gluconate and inhibits the utilization of glucose or fructose.

Glueose-6-phosphate dehydrogenase has been purified 22fold. It utilizes either NADP of NAD as coenzyme; it requires magnesium ions for maximal activity. The dehydrogenation reaction is competitively inhibited by rather high concentrations (2--6 mM) of ATP, and in a similar fashion by phosphoenolpyruvatc. Homotropic or heterotropic interactions between substrate molecules were not detected. The effect of ATP is relieved by equimolar concentrations of magnesium.