Which kinetic property would Enzyme X display as it binds its normal substrate
and catalyzes its reaction?
It could have an initial velocity independent of [S] when [S] < K
It could have a K
value that decreases as [S] decreases from 3.0 mM to
It could double the rate of its reaction as [S] increases from 3.0 mM to
It could have a Vmax value that is dependent on [S] when [S] < K
Enzyme Y is allosterically inhibited by ribose and also inhibited by covalent
modification with phosphate. Which is a characteristic of its regulation?
Y can covalently bind both ribose and phosphate to specific amino acids
within the protein.
Y can establish an equilibrium with either ribose or phosphate to reduce
the activity of the enzyme.
Y can bind both ribose and phosphate to a regulatory subunit with the help
of extra enzymes.
Y can undergo reversible conformational changes when either ribose or
phosphate binds to the enzyme.
The reactions of two enzymes, Enzyme A and Enzyme B, are studied at pH = 7.0. Both
enzymes produce glucose and have the same V
. Enzyme A has a K
of 2.0 mM while
Enzyme B has a K
of 5.0 mM. (Questions 38-44)
38. ______ Which characteristic will be shared by these two enzymes?
a) Both will increase the rate of their reaction by increasing the energy of the
Both will properly orient the substrate for their reaction by forming
covalent bonds with the substrate.
Both will decrease the activation energy of their reaction by being
complementary to the transition state.
Both will shift the equilibrium of their reaction by lowering the energy
level of the product.
39. ______ Which property will Enzyme A likely have in common with most other
a) It can bind the substrate reversibly using specific amino acids.
It can contain a dozen active sites each of which can bind a substrate
c) It can undergo a small change in primary structure as the substrate binds.
d) It can be required in stoichiometric amounts in order to bind the correct