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Michaelis-Menten Kinetics. Regardless of the number of substrates, a reaction is said to obey Michaelis-Menten kinetics if the rate equation can be expressed in the following form:

Regardless of the number of substrates, a reaction is said to obey Michaelis-Menten kinetics if the rate equation can be expressed in the following form:

........ (13)

which can be regarded as a generalization of Eqn (11). (Z is used here as an example of a product as suggested in Section 2.) Each term in the denominator of the rate expression contains unity or any number of product concentrations in its numerator. and a coefficient k and any number of substrate concentrations raised to no higher than the first power in its denominator. The constant k ₀ corresponds to k ₀ in Eqn (11); each other coefficient is assigned a subscript for each substrate concentration in the denominator of the term concerned and a superscript for each product concentration in the numerator. The term 1/ k ₀ must be present, together with one term for each substrate of the form 1/ k _A [A], but the terms in products of concentrations. such as those shown in Eqn (13) with coefficients k _AB and , may or may not be present. It is sometimes convenient to write the equation in a form in which each k is replaced by its reciprocal, symbolized by with the same subscripts and superscripts, i.e. = l/ k ₀, = l/ k _A, = 1/ k _AB, , etc. These reciprocal coefficients are called Dalziel coefficients.

Note The conventional Scottish pronunciation of this name may be expressed in the International Phonetic Alphabet as [di:'jel], with only slightly more stress on the second syllable than the first.

Eqn (13) can be applied to reactions with any number of substrates and products and can also be extended to some kinds of inhibition by substrate, i.e. to the simpler kinds of non-Michaelis-Menten kinetics. It is thus an equation of considerable generality. It is simplest, however, to consider terminology in the context of a two-substrate reaction, and this will be done in Section 5.2.

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