Purification and Regulatory Properties of Fructose 1,6-Diphosphatase from Hydrogenomonas eutropha
AUTOR(ES)
Abdelal, Ahmed T.
RESUMO
Fructose diphosphatase of Hydrogenomonas eutropha H 16, produced during autotrophic growth, was purified 247-fold from extracts of cells. The molecular weight of the enzyme was estimated to be 170,000. The enzyme showed a pH optimum of 8.5 in both crude extracts and purified preparation. The shape of the pH curve was not changed in the presence of ethylenediaminetetraacetic acid. The enzyme required Mg2+ for activity. The MgCl2 saturation curve was sigmoidal and the degree of positive cooperativity increased at lower fructose diphosphate concentrations. Mn2+ can replace Mg2+, but maximal activity was lower than that observed with Mg2+ and the optimal concentration range was narrow. The fructose diphosphate curve was also sigmoidal. The purified enzyme also hydrolyzed sedoheptulose diphosphate but at a much lower rate than fructose diphosphate. The enzyme was not inhibited by adenosine 5′-monophosphate but was inhibited by ribulose 5-phosphate and adenosine 5′-triphosphate. Adenosine 5′-triphosphate did not affect the degree of cooperativity among the sites for fructose diphosphate. The inhibition by adenosine 5′-triphosphate was mixed and by ribulose 5-phosphate was noncompetitive. An attempt was made to correlate the properties of fructose diphosphatase from H. eutropha with its physiological role during autotrophic growth.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=245764Documentos Relacionados
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