Structural Biochemistry/Enzyme/steady state

The steady state assumption was proposed by George Briggs and John Haldane in 1924. In this assumption, the concentrations of the intermediates of a reaction remain the same even when the concentrations of starting materials and products are changing. Steady state occurs when the rate of formation and breakdown of the intermediate are equal. The steady state assumption relies on the fact that both the formation of the intermediate from reactants and the formation of products from the intermediate have rates much higher than their corresponding reverse reactions. In other words, steady state assumes that k1>>k-1 and k2>>k-2.

Example of steady state of enzyme can be found from Michaelis-menten enzyme kinetics. This enzyme kinetic has a model for rate equation which has a closed-form solution for the concentration of reactants and products in an enzymatic reaction. In particular, the steady-state approximation assumes a negligible rate of change in the concentration of the enzyme-substrate complex during the course of the reaction. The initial phase of the reaction was examined by using the stopped flow method, which makes it possible to mix enzyme and substrate and monitor the results within a millisecond. This method revealed an initial rapid burst of colored product, followed by its slower formation as the reaction reached the steady state.