title: One hundred fold increased activity of Aeromonas aminopeptidase by sequential substitutions with Ni(II) or Cu(II) followed by zinc.
abstract: Full substitution of Cu(II) or Ni(II) for the two g-atom zinc in Aeromonas aminopeptidase hyperactivates the enzyme 6.5 and 25 fold respectively. Even greater enhancements of activity can be achieved with mixed metal substitutions. Thus, apoenzyme reactivated by first adding one g-atom zinc followed by one g-atom of either Cu(II) or Ni(II) is 15 and 22 times more active than the native enzyme. Reversing the order, i.e. by first adding either one g-atom Cu(II) or Ni(II) followed by one g-atom zinc, activates the enzyme nearly 100 fold. The order of metal addition is critical and suggests the existence of two non-identical metal sites, each with a different function.
mesh_terms: D000333:Aeromonas / Q000201:enzymology*; D000626:Aminopeptidases / Q000378:metabolism*; D001051:Apoenzymes / Q000378:metabolism; D003300:Copper / Q000494:pharmacology*; D004789:Enzyme Activation; D007700:Kinetics; D009532:Nickel / Q000494:pharmacology*; D015032:Zinc / Q000494:pharmacology*
chemical_list: D001051:Apoenzymes; D003300:Copper; D009532:Nickel; D000626:Aminopeptidases; D015032:Zinc