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Answers to Chapter 22 Practice Test
1.
a.
A catalyst increases the equilibrium constant of a reaction.
F
b.
An acid catalyst donates a proton to the substrate, and a base catalyst removes a proton
from the substrate.
T
c.
The reactant of an enzyme-catalyzed reaction is called a substrate.
T
d.
Complexing with a metal ion increases the
p
K
a
of water.
F
2.
It protonates the leaving group to make it a better leaving group.
3.
a.
rate
pH 5.7
b.
rate
pH 5.7
4.
HN N
CH
2
His
57
CH
2
CO
−
O
Asp
102
HN NH
CH
2
His
57
CH
2
CO
−
O
Asp
102
+
Ser
195
CH
2
O
H
R
C
NHR
O
Ser
195
CH
2
O
R
C
NHR
O
−
rst step
a.
base catalyst
b.
nucleophilic catalyst
c.
It stabilizes the positive charge on histidine.