Enzyme catalysis and Michaelis Menton Equation
MCQs for CSIR NET & GATE
Chemical Kinetics
Topic wise Asignment-7
Q1. The expression for
the equilibrium constant (Keq) for the enzyme catalyzed reaction
given below, is
(a) k1k3 / k2k4
(b) k1k2 / k3k4
(c) k2k3 / k1k4
(d) k1k4 / k2k3
Q2. In an enzyme catalyzed reaction
k2=
3.42 x 104 s-1. If [E]o= 1 x 10-2
mol dm-3, the magnitude of maximum velocity and turn over number using
Michaelis-Menten kinetics are
a)
3.42 x 102 mol dm-3 s-1;
3.42 x 104 s-1
b)
3.42 x 106 mol dm-3 s-1;
3.42 x 104 s-1
c)
3.42 x 104 mol dm-3 s-1;
3.42 x 106 s-1
d)
3.42 x 104 mol dm-3 s-1;
3.42 x 102 s-1
Q3. The slope and intercept obtained from 1/r
against 1/[S] of an enzyme catalyzed reaction are 300 and 2 x 105,
respectively. The Michaelis-Menten constants of the enzyme in this reaction is
(a) 5 x 106 M
(b) 5 x 10-6 M
(c) 1.5 x 103 M
(d) 1.5 x 10-3 M
Q4. For an enzyme-substrate reaction
The slope and
the intercept of the plot between 1/r and 1/[S] are 10-2 s and 102
M-1 s, respectively. If
Eo= 10-6 M and k-1/k2= 1000, the
value of k1 will be close to (in units of M-1 s-1)
[r is the rate of reaction and Eo is the initial concentration of
the enzyme]
(a) 1 x 1011
(b) 1 x 104
(c) 1 x 108
(d) 1 x 106
Q5. The Lineweaver-Burk Plot of (initial rate)-1
vs (initial substrate concentration)-1 for an enzyme catalyzed
reaction following Michaelis-Menten mechanism, the y-intercept is 5000 M-1s.
If the initial enzyme concentration is 1 x 10-9 M, the turnover
number is
(a) 2.5 x 103
(b) 1.0 x 104
(c) 2.5 x 104
(d) 2.0 x 105
Q6. For an enzyme catalyzed reaction, a
Lineweaver-Burk plot gave the following data:
Slope= 40s,
intercept= 4 (mmol dm-3 s-1)-1
If the
initial concentration of enzyme is 2.5 x 10-9 mol dm-3,
what is the catalytic efficiency (dm3 mol-1 s-1)
of the reaction?
(a) 105
(b) 106
(c) 107
(d) 104
Q7. For an enzyme-substrate reaction the Michaelis
constant is 0.042 mol dm-3. The rate of this reaction is 2.45 x 10-5
mol dm-3 s-1 when the substrate concentration is 0.89 mol
dm-3. The maximum velocity (mol dm-3 s-1) of
this enzyme catalysis is
(a) 2.57 x 10-5
(b) 2.45 x 10-5
(c) infinite
(d) 1.31 x 10-5
Q8. Vmax and Km for an enzyme
catalyzed reaction are 2.0 x 10-3 Ms-1 and 1.0 x 10-6
M, respectively. The rate (s-1) of the reaction when the substrate
concentration is 1.0 x 10-6 is
(a) 3.0 x 10-3
(b) 1.0 x 10-3
(c) 2.0 x 10-3
(d) 0.5
Q9. For an enzyme substrate reaction, a plot between
1/v and 1/[S] yields a slope of 40 s. If the enzyme concentration is 2.5 μM, then the catalytic efficiency (L mol-1
s-1) of the enzyme is
(a) 40
(b) 10-4
(c) 107
(d) 104
Ans Key
Q1.b Q2.a Q3.d Q4.a Q5.d Q6.a Q7.a Q8.b Q9.d