Question

The N enzyme and its two substrates, D and W

a. Use the following datat and the attached graph paper to determine Km and Vmax for the N hydrolysis of its D substrate and of its W substrate.

b. Choose ONE substrate and use the following data to determine Km and Vmax from a linear graph, then calculate the Kcat and Kcat/Km if the enzyme concentration is 1.5ng/microliter.

c. For which of these two substrates does the N enzyme have least affinity?

[D] (mM)	Vo (nmoles/min)	[W] (mM)	Vo (nmoles/min)
2.1	2	1.3	1
4.2	3.4	2.6	1.7
8.4	5.5	5.2	2.8
16.8	8.5	10.4	4.3
25	10	15	5
50	11	30	5.5

Answer 1

From the given data

Drawn below are two plots doe D and W

a. for D

Km = 80 mM

Vmax = 2.07 nmol/min

for W

Km = 33.33 mM

Vmax = 1.0367 nmol/min

b. For D

Kcat = Vmax/[Et]

        = 2.07/1.5

        = 1.38

Kcat/Km = 1.38/80 x 10^6

              = 1.725 x 10^-8

Plots