A totally different approach to analyzing enzyme kinetic data involves plotting many lines onto the experimental data; it was introduced in 1974 by Eisenthal and Cornish-Bowden.(3) For this procedure a Cartesian a-is-system is drawn with v0 on the ordinate and [A]0 on the abscissa. With the data pairs ([A]0i,v0i), i = 1,...,N, a straight line is drawn to pass through the points (-[A]0i, 0) and (0, v0i). The intersection of this line with others, similarly drawn, occurs at as many different points as there are data pairs. In other words, since experimental data are never error free, a set of values {Km, Vma-}j, j = 1,...,N-1, is obtained. The ne-t step in the analysis is to arrange the respective values of Km,j and Vma-,j into two separate sets, in ascending order. It has been shown that the 'statistically best estimate' of the two parameters is given by the respective median (middle) values in the set.®
Was this article helpful?