Abstract
The presence of a divalent metal ion together with a catalytic amount of inosine-5'-diphosphate (IDP) are essential for the activation of phosphoenolpyruvate carboxykinase purified from kidney of Arabian camels. With decreasing order of effectiveness, the carboxylating activity was supported by the metal ions, Mn2+, Cd2+ and Mg2+. Combination of Mg2+ with micromolar concentrations of Mn2+ or Co2+ recovered full activity. However, high concentration of Cd2+ proved to be inhibitory, when combined with Mn2+ or Co2+ plus Mg2+. Gluconeogenesis regulation is assumed to run principally via the control of PEPCK. This plays an important role in maintaining a high blood glucose level in camels, in contrast to ruminants (in jensu strictu) which have a low glucose level in blood.