ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary In Nocardia opaca strain 1b the key enzymes of the Entner-Doudoroff pathway, 6-phosphogluconate dehydrase and 2-keto-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 gluconate-grown cells. Molecular hydrogen represses the adaptation to fructose, glucose, or gluconate and inhibits the utilization of glucose or fructose. Glucose-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 phosphoenolpyruvate. Homotropic or heterotropic interactions between substrate molecules were not detected. The effect of ATP is relieved by equimolar concentrations of magnesium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00409943
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