CHAPTER 1General Principles & Energy Production in Medical Physiology 25
FIGURE 1–26 Fatty acid oxidation. This process, splitting off two carbon fragments at a time, is repeated to the end of the chain.
FIGURE 1–27 Formation and metabolism of ketone bodies. Note the two pathways for the formation of acetoacetate.
OH+ HS-CoA
——
OH
H α,β-Unsaturated fatty acid –CoA
β-Keto fatty acid –CoA
β-Hydroxy fatty acid –CoA
"Active" fatty acid + Acetyl –CoA
——
C
O
H 2 O+ R
——
O
CH 2 CH 2 CH 2 CH 2
S
R
CoA+ HS-CoA
——
C CS
O
——
O
R CH 2 CoA
——
C S CoA + CH 3 CS
O
——
O
R
——
C
O
R C CH 2
Mg^2 +
ATP ADP
Fatty acid
Oxidized
flavoprotein
Reduced
flavoprotein
"Active" fatty acid
C S CoA
H 2 O+ R
——
O
CoA CH CH C S CoA
NAD+ NADH+ H+
R = Rest of fatty acid chain.
S
——
C
O
CH 3 CoA+ CH 3 S
——
C
O
CoA
2 Acetyl-CoA Acetoacetyl-CoA
——
C
O
CH 3 CH 2 S
——
C
O
CoA+ HS-CoA
β-Ketothiolase
CH 3 C CH 2 SC CoA+ H 2 O
Acetoacetyl-CoA
Acetyl-CoA+ Acetoacetyl-CoA
HMG-CoA Acetoacetate+ H++ Acetyl-CoA
Acetoacetate
Acetoacetate
Acetone
3-Hydroxy-3-methylglutaryl-CoA
(HMG-CoA)
β-Hydroxybutyrate
CH 2
—
C
OH
CH 3
CH 2
C S CoA + H+
CH 2
–CO 2
CH 3 C C O− CO 2 + ATP
CH 3 C CH 3
+ H+
CH 3 CHOH CH 2 O−
——
C
O
+ H+
CH 3 C CH 2 C O−
COO−
+ H++ HS-CoA
Deacylase
(liver only)
+2H –2H
Tissues except liver
——
O
——
O
——
O
——
O
——
O
——
O
——
O
——
O