Limitations of Augustinsson plots.
The Augustinsson plot transforms the Michaelis-Menten equation by graphing velocity, v, as a function of velocity/substrate, v/s. The plot is linear with a negative slope for a single class of saturable sites and curvilinear for multiple classes of sites. Statistically, Augustinsson plots suffer from the limitation that there is no true independent variable. Experimental errors form a Gaussian distribution that rests neither parallel to the v axis nor v/s axis, but rather along a line emanating from the origin. Widening the range of s values produces increasingly large errors in the calculated Km and Vm values, especially when multiple sites are present. Exact data containing no error produces accurate constants using either the Michaelis-Menten or Augustinsson equation. With Km and Vm constants previously derived by fitting data with the statistically valid Michaelis-Menten equation, the Augustinsson plot may be used accurately to display multiple site data.
Dombi
G W
GW
Plastic Surgery Division, Wayne State University, Detroit, MI 48201.
D000465:Algorithms; D003627:Data Interpretation, Statistical; D007700:Kinetics; D008432:Mathematical Computing; D008838:Microcomputers; D012044:Regression Analysis; D013223:Statistics as Topic