The roles of magnesium ions in the reaction catalysed by phosphofructokinase from Trypanosoma brucei. |
| |
Authors: | C N Cronin and K F Tipton |
| |
Institution: | Department of Biochemistry, Trinity College, Dublin, Ireland. |
| |
Abstract: | The involvement of Mg2+ ions in the reaction catalysed by phosphofructokinase from Trypanosoma brucei was studied. The true substrate for the enzyme was shown to be the MgATP2-complex, and free Mg2+ ions are also required for enzyme activity. At concentrations of MgATP2- of 2.92 mM and greater, and a fructose 6-phosphate concentration of 1 mM and in the presence of EDTA as a Mg2+ buffer, the Km value for Mg2+ was determined to be 294 +/- 18 microM. Neither MgATP nor free ATP is an inhibitor of the enzyme, although apparent inhibition by the latter can be observed as a consequence of the decrease in free Mg2+ by chelation. |
| |
Keywords: | |
|
|