V max for an enzyme catalyzed reaction a generally

28. V
max
for an enzyme-catalyzed reaction:
A) generally increases when pH increases.
B) increases in the presence of a competitive inhibitor.
C) is limited only by the amount of substrate supplied.
D) is twice the rate observed when the concentration of substrate is equal to the K
m
E) is unchanged in the presence of a uncompetitive inhibitor.
.
Page 8

29. Enzyme X exhibits maximum activity at pH = 6.9. X shows a fairly sharp decrease in
its activity when the pH goes much lower than 6.4. One likely interpretation of this pH
activity is that:
30. Phenyl-methane-sulfonyl-fluoride (PMSF) inactivates serine proteases by binding
covalently to the catalytic serine residue at the active site; this enzyme-inhibitor bond is
not cleaved by the enzyme. This is an example of what kind of inhibition?
31. Both water and glucose share an —OH that can serve as a substrate for a reaction with
the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a
million times more reactive as a substrate than water. The BEST explanation is that:
32. A good transition-state analog:
A) binds covalently to the enzyme.
B) binds to the enzyme more tightly than the substrate.
C) binds very weakly to the enzyme.
D) is too unstable to isolate.
Page 9

E) must be almost identical to the substrate.
33. A transition-state analog: