@article{mbs:/content/journal/micro/10.1099/00221287-113-2-347, author = "Amachi, T. and Bowien, B.", title = "Characterization of Two Fructose Bisphosphatase Isoenzymes from the Hydrogen Bacterium Nocardia opaca 1b", journal= "Microbiology", year = "1979", volume = "113", number = "2", pages = "347-356", doi = "https://doi.org/10.1099/00221287-113-2-347", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-113-2-347", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "Summary: Two distinct forms of fructose 1,6-bisphosphatase, designated form A and form B, have been partially purified from autotrophically grown cells of the hydrogen bacterium Nocardia opaca 1b. Form A was present when the organism was grown under autotrophic conditions but was not synthesized during heterotrophic growth. Form B was detected in both autotrophically and heterotrophically grown organisms, suggesting that it is a constitutive enzyme. The molecular weights were estimated to be 140000 for form A and 190000 for form B. Both purified enzymes showed fructose bisphosphatase as well as sedoheptulose bisphosphatase activity, with pH optima of 8·2 and 8·8 to 9·0 for forms A and B, respectively. The ratio of fructose bisphosphatase to sedoheptulose bisphosphatase activity was 0·6 for form A and about 4·5 for form B. The enzymes required Mg2+ for activity; Mn2+ could only partially replace Mg2+. Form A was inhibited by ATP and ribulose bisphosphate. AMP exerted a strong allosteric inhibition on form B which was also inhibited by NAD+ and NADH. Phospho eno/pyruvate activated form B. On the basis of these results, different physiological roles for the two forms of fructose bisphosphatase are suggested.", }