Question

Beta-galactosidase follows Michaelis-Menten kinetics. A 5 micromolar solution of beta-galactosidase catalyzes the formation of 0.8 mmoles ortho-nitrophenol s-1 when saturated with the substrate ortho-nitrophenyl-beta-galactoside. What is beta-galactosidase's kcat?

Answer 1

Answer : The beta-galactosidase's
`K_(cat)` is,
`160s^(-1)`

Explanation :

Michaelis-Menten formula used :

`V_o=(V_(max))/(K_(cat))`

where,

`V_o` = initial concentration =
`5\mu mol=5* 10^(-6)mol`

`V_(max)` = maximum concentration =
`0.8mmol.s^(-1)=0.8* 10^(-3)mol.s^(-1)`

`K_(cat)` = Michaelis-Menten constant = ?

Now put all the given values in the above formula, we get:

`5* 10^(-6)mol=(0.8* 10^(-3)mol.s^(-1))/(K_(cat))`

`K_(cat)=160s^(-1)`

Therefore, the beta-galactosidase's
`K_(cat)` is,
`160s^(-1)`