Effect of H+ on the K+ activation of adenosine-5'-monophosphate aminohydrolase.
The activation of adenosine-5'-monophosphate aminohydrolase from rabbit skeletal muscle by H+ has been demonstrated. Evidence is presented which indicates that the binding of H+ and K+ is linked, in that the dissociation constant (KA) for K+ activation is reduced as the pH is lowered. Concomitantly, the pK of several enzyme functional groups is changed when K+ is added to a solution of enzyme. This change is pK results in an uptake or release of H+, depending on the pH, and shows that K+ interacts with the enzyme to achieve its effect. The uptake or release of H+ provides a simple method of following conformational changes in the enzyme following interaction of K+. The KD for K+ interaction monitored by following pH changes is the same within experimental error as that measured from kinetic data.
D000659:AMP Deaminase / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D009709:Nucleotide Deaminases / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D011817:Rabbits
D009709:Nucleotide Deaminases; D000659:AMP Deaminase; D011188:Potassium