Triacylglycerol Synthesis

1
Triacylglycerol Synthesis

• Fatty acyl-CoA
• DHAP reduction to glycerol-PO4 or
• Glycerol kinase to glycerol-PO4
• Two esterifications
• Diacylglycerol-PO4 intermediate
• Triacylglycerol

2
Triacylglycerol Biosynthesis
glycerol kinase
glycerol-PO4 dehydrogenase
DHAP
Glycerol-PO4
Phosphatidic acid
Phospholipid biosynthesis
1,2 Diacylglycerol (DAG)
3
Question

• Can a triacylglycerol (triglyceride) storage fat
  be synthesized entirely from glucose, i.e., every
  carbon in the fat comes from a sugar?
• Answer YES

4
Phosphatidic Acid
Phospholipid Biosynthesis (smooth ER)
Polar component
choline, serine, ethanolamine, etc
Glycerophospholipids

Phosphatidylcholine or lecithin
5
Strategy of Glycerophospholipid Biosynthesis

• Activate diacylglycerol
• Activate appending moiety (salvage)

6
Bacteria (Prokaryotes)
Activate Phosphatidic acid
CDP-diacylglycerol PPi
Phosphatidic acid CTP
7
Bacteria (Prokaryotes)
CDP-diacylglycerol
Phosphatidylserine
Phosphatidylglycerol-3-PO4
Phosphatidylethanolamine
Cardiolipin
8
Eukaryotes
ATP
Glycerol
Glycerol-3-PO4
DHAP
FA-CoA
1-Acyl-DHAP
Phosphatidic acid
NADPH
DAG
1-Acyl-glycerol-3-PO4
ATP
CTP
CDP-diacylglycerol
ethanolamine (CDP-ethanolamine)
choline (CDP-choline)
Serine (phosphatidylethanolamine)
Glycerol (CDP-diacylglycerol)
Inositol (CDP-diacylglycerol)
1,2 DAG
Cardiolipin (phosphatidylglycerol)
9
N
H
2
N
O
O
O
N

H
P
O
P
O
C
H
C
H
N
O
C
H
2
2
2
3
O
O
O
H
O
ethanolamine
O
H
C
y
t
i
d
i
n
e

d
i
p
h
o
s
p
h
a
t
e

(
C
D
P
)

10
SALVAGE
Ethanolamine or choline
HO-CH2-CH2-NH3
Ethanolamine kinase or choline kinase
Phosphoethanolamine
CDP-ethanolamine
Phosphatidylethanolamine
Phosphatidylserine