The kinetics of @entity413 - XXXX oxidoreductase from Zymomonas mobilis.

@entity3884 @entity948 @entity73329 @entity5121 @entity1110 @entity6189 @entity413
@entity413 - @entity948 oxidoreductase operates by a classic ping-pong mechanism with a single site for all substrates: @entity413 , @entity948 , @entity73329 and @entity5121 . The Km values for these substrates were determined. The values of kcat are 200 s-1 and 0.8 s-1 for the forward and reverse directions respectively. The overall catalytic process consists of two half-reactions with alternate reduction of @entity1110 + and oxidation of @entity1110 tightly bound to the enzyme. Reduction of enzyme- @entity1110 + by @entity413 and oxidation of enzyme- @entity1110 by @entity73329 involve single first-order processes. The values of the rate constants at saturating substrate are 2100 s-1 and 8 s-1 respectively; @entity6189 isotope effects indicate that these are for the @entity3884 transfer step. Oxidation of enzyme- @entity1110 by @entity948 is first order with a limiting rate constant of at least 430 s-1. The reaction of enzyme- @entity1110 + with @entity5121 is biphasic, with rate constants for both phases less than 1 s-1. This behaviour is explained by a mechanism in which the slow cyclisation of the acyclic form of @entity948 follows its dissociation from the enzyme. The rate-determining steps for the overall reaction are probably dissociation of @entity73329 in the forward direction and @entity3884 transfer from @entity5121 to enzyme-bound @entity1110 + in the reverse direction.
