A Century of Enzyme Kinetics: Reliability of the K M and v max Estimates

The application of the quasi-steady-state approximation (QSSA) in bio-chemical kinetics allows the reduction of a complex biochemical system with an initial fast transient into a simpler system. The simplified system yields insights into the behavior of the biochemical reaction, and analyti-cal approximations can be obtained to determine its kinetic parameters. However, this process can lead to inaccuracies due to the inappropriate application of the QSSA. Here we present a number of approximate solu-tions and determine in which regions of the initial enzyme and substrate concentration parameter space they are valid. In particular, this illus-trates that experimentalists must be careful to use the correct approxima-tion appropriate to the initial conditions within the parameter space.