Pooling and comparing estimates from several experiments of a Michaelis constant for an enzyme.

Often the Michaelis constant of an enzyme will be determined several times. This may be done for various reasons such as ensuring reproducibility, comparing different enzyme preparations, or examining the effects of variations in experimental conditions. In these circumstances, two questions arise. First, how can the various estimates of the Michaelis constant be compared to determine whether they are the same within the limits of experimental variation? Secondly, if they are all the same, how can the values be combined to give an overall estimate? These questions are addressed here and a solution proposed in which the sets of data are pooled and analyzed with a separate maximum velocity for each set but a common Michaelis constant. The pooled data are partitioned in suitable ways and reanalyzed to examine, by means of a variance ratio test, whether a single Michaelis constant gives a satisfactory fit to the data.