"Acetylcholinesterase follows Michaelis-Menten kinetics. A 1.3 micromolar solution of acetylcholinesterase catalyzes the formation of 6.5 mmoles choline s-1 when saturated with acetylcholine. What is acetylcholinesterase's kcat?"

5000 s^-1

Explanation: Solution=

Using the formulae> Kcat=Vmax/Et

where

Vmax is the maximum rate of the reaction when all the enzymes are saturated.

Vmax= 6.5 mmoles/s

Et=1.3 uM

1 mmole= 1000 umole

Changing to micromoles/sec, gives=

Vmax=   6.5 mmoles/s \times 1000= 6500 micromoles/s

Bringng back the equation,  

>Kcat= Vmax/Et

= 6500/1.3

= 5000 /s

Therefore, our answer  is 5000 s^-1

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