moo Flashcards
A competitive inhibitor of an enzyme is usually
a. a highly reactive compound
b. a metal ion such as Hg2+ or Pb2+
c. structurally similar to the substrate.
d. water insoluble
structurally similar to the substrate.
Linear inhibition is sometimes called as
a. complete inhibition
b. incomplete inhibition
c. partial inhibition
d. mixed inhibition
complete
The types of inhibition pattern based on
Michaelis Menten equation are
a. competitive
b. non-competitive
c. uncompetitive
d. all of the above
all of the above
The effect of non-competitive inhibition on a
Lineweaver-Burk Plot is that
a. it can move the entire curve to the right
b. it can change the y-intercept
c. it can change the x-intercept
d. all of thes
can change the y-intercept
The rate-determining step of Michaelis Menten
kinetics is
a. the complex formation step
b. the complex dissociation step to produce
product
c. the product formation step
d. Both (a)and(c)
the complex dissociation step to produce
product
In competitive inhibition a factor is obtained
from the measurement of
a. Vmax
b. KM
c. Y-intercept in Lineweaver-Burk Plot
d. None of these
Km
Which of these proteases is not a cysteine active
site protease?
a. Calpain
b. Cathepsin D
c. Papain
d. None of the above
cathepsin D
Given an enzyme with a Km = 10m M and Vmax
= 100 m mol/min. If [S] = 100 m M, which of
the following will be true?
a. A 10-fold increase in Vmax would increase
velocity 10-fold y
b. A 10-fold decrease in Km would increase
velocity
c. Both (a) and (b)
d. A 10-fold increase in Vmax would decrease
velocity 20-fold
A 10-fold increase in Vmax would increase
velocity 10-fold y
The conformational change in an enzyme after
the substrate is bound that allows the chemical
reaction to proceed, can be explained by
a. induced fit
b. transition
c. fit and fine
d. Pasteur
INDUCED FIT
. The active site of an enzyme remains
a. at the center of globular proteins
b. rigid and does not change shape
c. complementary to the rest of the molecule
d. none of the above
none of the above
Which category of enzymes belongs to class
two in the international classification?
a. Hydrolases
b. Ligases
c. Transferases
d. Isomerase
transferases
The Woolf-Augusteinsson-Hofstee plot of ν
versus ν/[S] and the Eadie-Scatchard plot of
ν/[S] versus ν do not involve reciprocals of ν
therefore are considered to be more reliable
when the error in v is
a. non-significant
b. significant
c. nothing to do with the reliability
d. non-significant in selected cases
significant
The relationship between Keq, Km and Vmax is
known as
a. Haldane equation
b. Michaelis Menten equation
c. Numerical solution approach
Haldane
. The reciprocal equation for non-competitive
inhibition can be arranged to the equation for
the
a. Dixon plot
b. Woolf-Augusteinsson-Hofstee plot
c. Eadie-Scatchard plot
d. Hanes-Woolf plot
Dixon plot
Which of the following statements is true for
enzymatically catalyzed reaction?
a. The activation energy of the reaction is
lowered so that a larger proportion of the
substrate qualifies to overcome it
b. Additional substrate molecules are
energized to overcome the activation
energy of the reaction
c. The activation energy of the reaction is
increased, thus decreasing the likelihood
that any substrate molecules will overcome
it
d. The activation energy of the reaction is
lowered so that fewer substrate molecules
can overcome it
The activation energy of the reaction is
lowered so that a larger proportion of the
substrate qualifies to overcome it
Which of the following common drugs is not a
specific enzyme inhibitor?
a. Iodine
b. Methotrexate
c. Sulfanilamide
d. Penicillin
Iodine
In a Lineweaver-Burk Plot, competitive
inhibitor shows which of the following effect?
a. It moves the entire curve to right
b. It moves the entire curve to left
c. It changes the x-intercept
d. It has no effect on the slope
changes the x-intercept
Which of the following statements is not true?
a. Enzymes are proteins that bind to specific
substrates and increase the velocity of
reactions involving those substrates
b. Enzymes function by overcoming the
activation energy barrier of a reaction
c. Enzymes make thermodynamically
favorable reactions to proceed; they cannot
make unfavorable reactions to occur
d. Enzymes only function when they are in
intact cells
Enzymes only function when they are in
intact cells
Non-competitive inhibitor of an enzyme
catalyzed reaction
a. decreases Vmax
b. binds to Michaelis complex (ES)
c. both (a) and (b)
both
An enzyme and a reactant molecule maintain
relationship as
a. a temporary association
b. an association stabilized by a covalent bond
c. one in which the enzyme is changed
permanently
d. non complementary binding
temporary association
An enzyme is assayed at an initial substrate
concentration of 2 x 10-5M. In 6-minute, half
of the substrate is used. The Km for the
substrate is 2 x 10-3M. The value of k in minute
is
a. 0.115
b. 0.42
c. 0.093
d. 6.693
0.115
The plot commonly used for determining the
value of Vmax is
a. Lineweaver Burk plot
b. Langmuir plot
c. Eadie Hofstee plot
d. all of these
all of these
Quasi steady state is also known as
a. Michaelis Menten approach
b. Briggs-Haldane approach
c. Pseudo steady state
d. all of the abov
Pseudo steady state
Which of these enzymes contains a Zinc (Zn)
ion?
a. Carboxypeptidase A
b. Phosphorylase B kinase
c. Tyrosine hydroxylase
d. Phosphodiesterase
Carboxypeptidase A
A noncompetitive inhibitor of an enzymecatalyzed reaction
a. increases KM and increases Vmax
b. increases KM and reduces Vmax
c. reduces KM and increases Vmax
d. reduces KM and reduces Vmax
ncreases KM and reduces Vmax
An allosteric inhibitor of an enzyme usually
a. participates in feedback regulation
b. denatures the enzyme
c. is a hydrophobic compound
d. causes the enzyme to work faster
participates in feedback regulation
A classical uncompetitive inhibitor is a
compound that binds
a. reversibly to the enzyme substrate complex
yielding an inactive ESI complex
b. irreversibly to the enzyme substrate
complex yielding an inactive ESI complex
c. reversibly to the enzyme substrate complex
yielding an active ESI complex
d. irreversibly to the enzyme substrate
complex yielding an active ESI complex
reversibly to the enzyme substrate complex
yielding an inactive ESI complex
. Which graphical method is used to determine
an enzyme degree of cooperativity?
a. Hill plot
b. Koshland curve
c. Michaelis-Menten hyperbola
d. Can not be determined
Hill plot
The ratio of the amount of a protein present in
a sample, which is used as a measure of
purification, is known as
a. specific activity
b. relative activity
c. purity ratio
d. all of these
specific activitiy
If a reaction occurs in the absence of inhibitor
with rate ν0 and in the presence of inhibitor
with rate νi, the degree of inhibition is defined
as
a. (ν0 - νi)/ν0
b. (ν0 + νi)/ν0
c. (ν0νi)/ν0
d. (ν0-νi)/νi
a. (ν0 - νi)/ν0
The rate equation in competitive inhibition
based on Michaelis Menten equation is given
by
a. rmaxS/(Km(1+I/Ki) +S))
b. rmaxE/(Km(1+I/Ki) +S))
c. rmaxI/(Km(1+I/Ki) +S))
d. rmaxS/(Km(1+I/Ki))
rmaxS/(Km(1+I/Ki) +S))
Classical noncompetitive inhibition is obtained
only under
a. slow equilibrium conditions
b. moderate equilibrium conditions
c. rapid equilibrium conditions
d. non-equilibrium conditions
rapid eq
In the steady state the material balance equation
for any component of a system is
a. rate of addition + rate of removal - rate of
formation = 0
b. rate of addition - rate of removal + rate of
formation = 0
c. rate of addition + rate of removal + rate of
formation = 0
d. none of the above
rate of addition - rate of removal + rate of
formation = 0
For an enzyme that displays Michaelis-Menten
kinetics, the reaction velocity (as a fraction of
Vmax) observed at [S] = 2 KM will be
a. 0.09
b. 0.33
c. 0.66
d. 0.91
0.66
Predominantly uncompetitive inhibition may
be called when
a. competitive inhibition is greater than
uncompetitive inhibition
b. competitive inhibition is smaller than
uncompetitive inhibition
c. competitive inhibition is equal to
uncompetitive inhibition
d. none of the above
. competitive inhibition is greater than
uncompetitive inhibition
An enzyme has a Km of 4.7 x 10-5M. If the
Vmax of the preparation is 22m moles liter-1
min-1, what velocity would be observed in the
presence of 2.0 x 10-4M substrate and 5.0 x 10-
5M of a competitive inhibitor?
a. 13.54μ moles liter-1min-1
b. 6.68μ moles liter-1min-1
c. 7.57μ moles liter-1min-1
d. 17.8μ moles liter-1min-1
13.54μ moles liter-1min-1
The rate equation in non-competitive inhibition
based on Michaelis Menten equation is given
by
a. rmaxS/ (Km + S) (1+I/Ki)
b. rmaxE/ (Km (1+I/Ki) +S))
c. VmaxS/ (Km + S) (1+I/Ki)
d. rmaxS/Km
rmaxS/ (Km + S) (1+I/Ki)
Which of the following statement(s) regarding
enzymes, is/are false?
a. Enzymes are always proteins that function
as catalysts
b. Enzymes provide activation energy for
reactions
c. Enzyme activity can be regulated
d. Enzymes may be used many times for a
specific reaction
Enzymes provide activation energy for
reactions
The slope of Lineweaver Burk plot for
Michaelis Menten equation is
a. Vmax/Km
b. Km/Vmax
c. 1/Km
d. Km*Vmax
Km/Vmax
The initial velocity, V0, of an enzyme catalyzed
reaction reaches Vmax as
a. [S] = KM
b. [S] = 10 * KM
c. 1/[S] = 1/KM
d. 1/[S] → 0
1/[S] → 0
The usual method(s) to solve rate equation of
simple enzyme kinetics is/are
a. Michaelis Menten approach
b. Briggs-Haldane approach
c. Numerical solution approach
d. all of these
all of these
Michaelis Menten equation can also be written
as
a. (-Cs)/r = (Cs/rmax)+(Km/rmax)
b. 1/r = (1/rmax)+(Km/(rmax.Cs))
c. r = rmax-(Km.r/Cs)
d. All of these
all of these
Which of the following step is assumed to be
the slowest step in the Michaelis Menten
equation?
a. The substrate consuming step
b. The product releasing step
c. Formation of enzyme substrate complex
d. None of these
product releasing step
When substrate [S] = KM (Michaelis-Menten
constant), the velocity of an enzyme catalyzed
reaction is about
a. 0.1 * Vmax
b. 0.2 * Vmax
c. 0.5 * Vmax
d. 0.9 * Vmax
0.5Vmax
A classical noncompetitive inhibitor has
a. no effect on substrate binding
b. no effect on substrate binding and vice
versa
c. significant effect on substrate binding
d. significant effect on substrate binding and
vice versa
no effect on substrate binding and vice
versa
The active site of an enzyme differs from an
antibody-antigen binding site in that the
enzyme active site
a. contains modified amino acids
b. catalyzes a chemical reaction
c. is complementary to a specific ligand
d. contains amino acids without side chains
catalyzes a chemical reaction
Enzymes are basically
a. Proteins
b. Vitamins
c. Fat
d. Carbohydrates
Proteins
Which of the following refers to pseudo steady
state?
a. d(CE)/dt = 0
b. d(Cp)/dt = 0
c. d(CES)/dt = 0
d. d(Cs)/dt = d(CES)/dt
d(CES)/dt = 0
Most enzymes work by
a. increasing energy of activation
b. decreasing energy of activation
c. not affecting energy of activation
d. none of the above
decreasing energy of activation
Which category of enzymes belongs to class 5
in the international classification?
a. Hydrolases
b. Isomerases
c. Oxido-reductases
d. Cyclase
Isomerases
Lock and key theory is based on the
compatibility of
a. enzyme and substrate
b. enzyme and product
c. enzyme and enzyme substrate complex
d. enzyme substrate complex and product
enzyme and substrate
When an enzyme is functioning at Vmax, the
rate of the reaction is limited by
a. the number of collisions between enzyme
and substrate
b. the number of substrate molecules in the
reaction
c. the concentration of the substrate
d. the rate at which the enzyme can convert
substrate to product
the rate at which the enzyme can convert
substrate to product
- The equation for the rate of product formation
for simple enzyme reaction is given by (Where
rmax, maximum reaction rate, Cs substrate
concentration, Cp product concentration ES,
CES enzyme-substrate concentration)
a. rp = rmax Cs/(Km+Cs)
b. rp= rmax CES/ (Km+ CES)
c. rp = rmax Cs/(Km+CES)
d. rp = rmax Cs/(Km+Cp)
rp = rmax Cs/(Km+Cs)
When [S] = 0.1 *KM, the velocity of an enzyme
catalyzed reaction is about:
a. 0.1 * Vmax
b. 0.3 * Vmax
c. 0.5 * Vmax
d. 0.7 * Vmax
. 0.1 * Vmax
