Effect of Steric Changes in Protein on the Kinetics of Enzyme Reaction : II. Steady-state Treatment of Reactions with One Substrate

Keleti, Tamás (1968) Effect of Steric Changes in Protein on the Kinetics of Enzyme Reaction : II. Steady-state Treatment of Reactions with One Substrate. ACTA BIOCHIMICA ET BIOPHYSICA ACADEMIAE SCIENTIARUM HUNGARICAE, 3 (3). pp. 247-258. ISSN 0001-5253

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Abstract

The theory and the equations of initial velocity of reactions with one substrate are elaborated, taking into account the steric changes in the enzyme and using the steady-state assumption. In the case of cyclic models the initial rate of enzyme action is a quadratic function of substrate concentration. In these cases a sigmoid relationship between the reaction velocity and the substrate concentration may be obtained without any further assumption on the cooperative interaction of subunits. In the case of non-cyclic models the initial rate of enzyme action is a hyperbolic function of substrate concentration, however, the maximum velocity and the Michaelis constant are the combination of the rate constant of the breakdown of the enzyme-substrate complex as well as of the formation and breakdown of this and of the rate constants of the preliminary elementary steps. The equations of initial velocities presented give also the steady-state treatment of different types of inhibition and activation. A general rule concerning the graphical evaluation of the equation of initial velocity of non-cyclic models is presented.

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