802 / 912
794 Chapter 25
Copyright © 2017 Pearson Education, Inc.
14.
Squalene, lycopene, and
b
-carotene are all synthesized in the same way. In each case, two halves are
synthesized (in a head-to-tail fashion) and then joined in a tail-to-tail linkage.
lycopene
-carotene
B
15.
SCoA
CoASH
H
2
O
CoAS
O
O
_
_
SCoA
aldol
addition
hydroxymethylglutaryl-CoA
O
O
O
_
SCoA
O
SCoA
OH
O
_
O
_
O
O
SCoA
+
+
O O
SCoA
Claisen
condensation
C
O
SCoA
SCoA
16.
One equivalent of NADPH is required to reduce the thioester to an aldehyde. The second equivalent of
NADPH is needed to reduce the aldehyde to an alcohol.
OOC
SCoA
OOH
_
NADP H
OOC
SCoA
O
_
_
NADP
+
NADP
+
+
OOC
H
O
_
NADP H
OOC
H
_
_
OOC
OH
_
OH
OH
OH
OH
O
BH
+
B