Biochemistry 6th Edition by Reginald Garrett,Charles Grisham

Exercise 13

Quantitative relationships between rate constants to calculate K m , kinetic efficiency (k cat /K m ) and V max -V
Acetylcholinesterase catalyzes the hydrolysis of the neurotransmitter acetylcholine:
Acetylcholine + H₂ O ? acetate + choline
The K m of acetylcholinesterase for its substrate acetylcholine is 9 x 10 -5 M. In a reaction mixture containing 5 nanomoles/mL of acetylcholinesterase and 150 ?M acetylcholine, a velocity v 0 = 40 ?mol/mL·sec was observed for the acetylcholinesterase reaction.
a. Calculate the V max for this amount of enzyme.
b. Calculate k cat for acetylcholinesterase.
c. Calculate the catalytic efficiency (k cat /K m ) for acetylcholinesterase.
d. Does acetylcholinesterase approach "catalytic perfection"?