Study of the relationship between estimates of enzyme kinetic parameters.

Previous indications of an intrinsic relationship between estimates of Km and Vmax calculated from the Michaelis-Menten equation have been explored further. A mathematically linear relationship could be established for the estimates of the two parameters. The relationship--the trend line--holds whether or not the experimental error is linked to the rate of reaction, the substrate concentration or both, provided that the distribution of errors is symmetrical. The practical implication is that enzyme variants with low values of Km and Vmax may not be distinguishable from those with high values of Km and Vmax.