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780 Chapter 24
Copyright © 2017 Pearson Education, Inc.
15.
pyruvate
alanine
CH
3
CH O
transamination
NH
3
+
_
C
O
CH
3
C O
_
C
O
O
16.
Protonated histidine
(p
K
a
=
6.0)
is not strong enough an acid to fully protonate the OH group to make it
a good leaving group (H
2
O) that would be able to leave in the first step of the elimination reaction, which
is required for an E1 reaction. Therefore, it is an E2 reaction with protonated histidine acting as a general-
acid catalyst to protonate the OH group as it departs.
17.
a secondary alcohol
18.
citrate and isocitrate (and the alkene intermediate generated during the conversion of citrate to isocitrate)
19.
_
O CH
C
O
C
O
2
CH
2
20.
S SH
O
R
C
R = OOCCH
2
CH
2
−
−
−
C C
O
O
R
OH
R
ʹʹ
C
S
+
CR
OH
R
ʹʹ
O
S S
H B
C
S
R
ʹ
N
NH(CH
2
)
4
E
O
SCoA
CoASH
+
O
R
C
HS SH
NH(CH
2
)
4
E
O
O
H–B
O
succinyl-CoA
R
ʹʹ
O
R
C
C
C
−
−
S
+
R
ʹ
N
R
ʹ
N
−
C S SH
R
ʹ
R
ʹʹ
O
O H B
C
S
+
NH(CH
2
)
4
R
ʹ
N
NH(CH
2
)
4