Kinetic Studies of Glyceraldehyde‐3‐Phosphate Dehydrogenase from Rabbit Muscle

Abstract
Initial rate studies at pH 7.6 with three aldehydes, product inhibition patterns with NADH and dead‐end inhibition with adenosine diphosphoribose show that the kinetic mechanism of glyceraldehyde‐3‐phosphate dehydrogenase from rabbit muscle cannot be ordered, and support an enzyme‐substitution mechanism. Deviations from Michaelis‐Menten behaviour are consistent with negative interactions in the binding of NAD+ and instability of the species E(NAD)3 and E(NAD)4. Inhibition with large concentrations of phosphate and arsenate indicates competition for a binding site for glyceraldehyde 3‐phosphate, and is not found with glyceraldehyde as substrate.