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QA - Multiple Choice

The concerted model for allosteric behavior was proposed by:
A. Koshland
B. Pauling
C. Pasteur
D. Monod, Wyman and Changeux
E. All of these
The behavior of allosteric enzymes
A. does not play any role in feedback inhibition in metabolic pathways
B. is strongly dependent on the presence of metal ions
C. is related to their ability to hydrolyze themselves
D. depends on changes in their quaternary structure on binding of substrates or inhibitors
The sequential model for allosteric enzymes was proposed by:
A. Koshland
B. Pauling
C. Pasteur
D. Monod, Wyman and Changeux
E. All of these
In the concerted model for allosteric enzymes
A. the relative affinities of substrate for the T and R conformations plays an important role in the cooperativity of the reaction.
B. the equilibrium between the T and R conformations plays a minor role.
C. the enzymatic activity of the T conformation is considerably higher than that of the R form.
D. it is possible to describe the reactions of all allosteric enzymes accurately.
Which of the following does not apply to the concerted model for subunit behavior:
A. Each subunit can exist in a relaxed (R) and taut (T) conformation.
B. All subunits will be in either the R or the T conformation at the same time.
C. Some subunits can be in the R state while others are in the T state.
In the concerted model, which state binds the substrate more tightly?
A. the relaxed (R) state
B. the taut (T) state
C. Both states bind equally well.
Allosteric enzymes must exhibit which of the following?
A. feedback inhibition
B. a phosphorylation site
C. general acid-base catalysis
D. a quaternary structure
What happens when a K-acting inhibitor is added to an allosteric enzyme system?
A. The apparent KM for the substrate increases.
B. The apparent KM for the substrate decreases.
C. The apparent Vmax for the substrate increases.
D. The apparent Vmax for the substrate decreases.
In a comparison of allosteric and non-allosteric enzymes
A. it is always possible to define a KM
B. it is always possible to define a Vmax
C. competitive inhibition is always a possibility
D. much of the terminology is completely unchanged
Where do allosteric inhibitors bind on an enzyme?
A. They always bind at a site different from the active site.
B. They always bind at the active site.
C. They can bind at either active site or another site.

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