Ukr.Biochem.J. 2012; Volume 84, Issue 2, Mar-Apr, pp. 93-104

On true and apparent Michaelis constants in enzymology. II. Is the equation K(m)(app) = K(s) + k(cat)/k(1) true for enzyme-catalysed reactions with activator participation?

S. O. Karakhim

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;

The article is dedicated to analysis of equation which expresses apparent Michaelis constant Kmapp of enzyme-catalysed reactions with activator participation by means of the substrate constant Ks and rate constant of enzyme-substrate complex decomposition kcat. It has been shown that although it is possible to record the mechanisms of such reactions as a scheme similar to Michaelis-Menten model and to derive equation of apparent Michaelis constant as Kmapp = Ks + kcat/k1, but this approach cannot be used for investigation of all reac­tions with activator participation. The equation mentioned above is not obeyed in the general case, it may be true for some mechanisms only or under certain ratio of kinetic parameters of enzyme-catalysed reactions.

Keywords: , , , , ,

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