Food Biochemistry and Food Processing (2 edition)

BLBS102-c08 BLBS102-Simpson March 21, 2012 12:8 Trim: 276mm X 219mm Printer Name: Yet to Come

8 Enzyme Activities 173

Figure 8.3.The Lineweaver–Burk double-reciprocal plot.

is, diluting the stock solution of substrate by two-, three-, four-,

five-,...fold (Copeland 2000).

Eadie–Hofstee Plots

The Michaelis-Menten equation can be rearranged to give

v=−Km(v/[S])+Vmaxby first multiplying both sides by

Km+[S], and then dividing both sides by [S]. The plot will give

a linear curve with a slope of−Kmand ayintercept ofvwhen

vis plotted againstv/[S] (Fig. 8.4). The Eadie–Hofstee plot has

the advantage of decompressing data at high substrate concen-

trations and being more accurate than the Lineweaver–Burk plot,

but the values ofvagainst [S] are more difficult to determine

(Eadie 1942, Hofstee 1959). It also has the advantage of observ-

ing the range ofvfrom zero toVmaxand is the most effective

plot for revealing deviations from the hyperbolic reaction when

two or more components, each of which follows the Michaelis-

Menten equation, although errors invaffect both coordinates

(Cornish-Bowden 1996).

Figure 8.4.The Eadie–Hofstee plot.

Figure 8.5.The Hanes–Wolff plot.

Hanes–Wolff Plots

The Lineweaver–Burk equation can be rearranged by multiply-

ing both sides by [S]. This gives a linear plot [S]/v=(1/Vmax)

[S]+Km/Vmax, with a slope of 1/Vmax,theyintercept of

Km/Vmax, and thexintercept of−Kmwhen [S]/vis plotted

as a function of [S] (Fig. 8.5). The plot is useful in obtaining

kinetic values without distorting the data (Hanes 1932).

Eisenthal–Cornish-Bowden Plots

(the Direct Linear Plots)

As in the Michaelis-Menten plot, pairs of rate values ofvand

the negative substrate concentrations [S] are applied along the

yandxaxis, respectively. Each pair of values is a linear curve

that connects two points of values and extrapolates to pass the

intersection. The location (x,y) of the point of intersection on

the two-dimensional plot representsKmandVmax, respectively

(Fig. 8.6). The direct linear plots (Eisenthal and Cornish-Bowden

Figure 8.6.The Eisenthal–Cornish-Bowden direct plot.