Abstract
<jats:p>Haldaneused the quasi-steady state assumption in theoretical analyses of two kinetic models of enzyme-catalysed reversible isomerisation reactions, but these analyses gave incorrect predictions of the parameters of the kinetic constants of the Henri-Michaelis-Menten equation. The errors were due to a false assumption made to obtain the equation in terms of an initial velocity, and his results were parameters for irreversible reactions. Correct derivations are given for a minimally adequate kinetic model of an isomerization, an alternative derivation is introduced, and the results are discussed briefly in terms of the teaching of enzyme kinetics and of the role of numerical methods in determining individual rate constants. The observations made here may have consequences for analyses of more complex reactions in which the same false assumption has been used.</jats:p>