Briggs-Haldane Kinetics: Properties of Mechanisms With More Than One Catalytic Cycle
The kinetic investigation of mechanisms with branched catalytic cycles is more difficult than that of unbranched mechanisms with the same reactancy. To see why, consider the general mechanism, shown in figure 6.1, by which a chemical group G is transferred from a donor molecule, GX, to an acceptor molecule Y in the forward direction and from GY to X in the reverse. It will be observed that the mechanism postulates both sequential and nonsequential branches, and that seven distinct enzyme-intermediates are involved. The full rate equation for this mechanism contains 672 terms in the denominator, and 112, of which half are negative, in the numerator. Furthermore, the several reactant concentrations appear in the equation raised to all powers up to Y3, GX2, X3 and GY2. The difficulties that such a mechanism could present to an investigator are as follows :
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