Question

The following data were obtained in an enzyme study: Use these data to construct a Michaelis-Menten plot, a Lineweaver-Burk plot, and an Eadie-Hofstee plot. Fit the data in the L-B and E-H plots and use the fit parameters to determine K_M and v_s in each case. Comment on how well the K_Ms and v_ss agree with each other.

Answer 1

[S] µM	v, µMmin-1	1/[S] µM-1	1/v, min/µM	v/[s] min-1
0	0	-	-	-
2	2.91	0.50	0.34	1.46
3	3.83	0.33	0.26	1.28
4	4.35	0.25	0.23	1.09
5	4.87	0.20	0.21	0.97
6	5.42	0.17	0.18	0.90
7	5.75	0.14	0.17	0.82
8	6.21	0.13	0.16	0.78
9	6.36	0.11	0.16	0.71
10	6.73	0.10	0.15	0.67

a) Michaelis-Menten Plot: Plot of Reaction rate, v vs substrate concentration, [S]

Michaelis-Menten Plot 10 [S], HM

b) Lineweaver-Burk Plot: Plot of 1/v vs 1/[S]

Lineweaver-Burk Plot 0.40 0.35 0.30 0.25 2 0.20 y 0.4817x+0.104 0.15 0.10 0.05 0.00 0.00 0.10 0.20 0.30 0.40 0.50 0.60

y-intercept = 0.104 = 1/Vs

Vs = 9.6 µMmin^-1

Slope = 0.4817 = Km/Vs

Km = 0.4817 * 9.6 = 4.63 µM

c) Eadie-Hoftee Plot: Plot of v vs v/[S]

Eadie-Hofstee Plot y:-4.7599X+9.7462m 0.60 0.80 1.00 1.20 1.40 1.60 v/[S], 1/min

y-intercept = 9.75 = Vs

Vs = 9.75 µMmin^-1

Slope = -4.76 = - Km

Km = 4.76 µM

*Results of Lineweaver-Burk and Eadie-Hoftee are close in value (<0.2 – 0.3 % difference).