text: The plot of  against  has often been called a "Michaelis–Menten plot", even recently, but this is misleading, because Michaelis and Menten did not use such a plot. Instead, they plotted  against , which has some advantages over the usual ways of plotting Michaelis–Menten data. It has  as dependent variable, and thus does not distort the experimental errors in . Michaelis and Menten did not attempt to estimate  directly from the limit approached at high , something difficult to do accurately with data obtained with modern techniques, and almost impossible with their data. Instead they took advantage of the fact that the curve is almost straight in the middle range and has a maximum slope of  i.e. . With an accurate value of  it was easy to determine  from the point on the curve corresponding to .
  This plot is virtually never used today for estimating  and , but it remains of major interest because it has another valuable property: it allows the properties of isoenzymes catalysing the same reaction, but active in very different ranges of substrate concentration, to be compared on a single plot. For example, the four mammalian isoenzymes of hexokinase are half-saturated by glucose at concentrations ranging from about 0.02 mM for hexokinase A (brain hexokinase) to about 50 mM for hexokinase D ("glucokinase", liver hexokinase), more than a 2000-fold range. It would be impossible to show a kinetic comparison between the four isoenzymes on one of the usual plots, but it is easily done on a semi-logarithmic plot.