Concepts in Biochemistry 3e

1
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
14
acetyl-CoA
Metabolic Map
Showing the main potential paths. Paths used
depends on tissue and metabolic state. Key
intermediates in boxes.
e-
ATP
2
Metabolism of Macronutrients Map
Key
glycolysis use glucose for energy
pentose-P path make NADPH /or ribose-5-P for
biosynthesis
3
glycogen breakdown utilize glycogen stores in
liver or muscle
4
glycogen synthesis store excess glucose in
liver or muscle
5
gluconeogenesis make glucose to maintain blood
glucose (liver) or replenish glycogen
(muscle)


6
7
8
export of glucose glucose transported out of
cell to maintain blood glucose (occurs
only in liver)
9
b-oxidation use dietary or stored fats for
energy
10
fatty acid synthesis store energy as
triacylglycerols in adipose tissue
11
protein synthesis and breakdown normal protein
turnover, breakdown rate may increase to
provide fuel of last resort
12
transamination reactions remove N from AAs for
catabolism
13
C-skeleton pathways carbon from AAs can be
used to a) make glucose to maintain blood
glucose (liver only) b) make CAC compounds to
increase rate of CAC c) make ATP by complete
oxidation (CAC ox-phos)
14
urea cycle remove toxic NH4, requires ATP as
energy source
15
AA synthesis multiple paths, convert
glycolysis CAC compounds into
C-skeletons of AAs, require ATP and NADPH
16
ketone body formation (in liver, exported as
fuel to other tissues)
17
3
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
14
acetyl-CoA
Brain

• high energy demand
• strong preference for
• glucose
• can adapt to use ketones

e-
ATP
4
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
Active skeletal muscle
6
14
acetyl-CoA

• high energy demand
• preferred fuels glycogen,
• glucose
• fats, proteins can be used
• lactate produced

e-
ATP
5
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
14
Recovering skeletal muscle
acetyl-CoA

• FAs used for energy
• lactate blood glucose
• used to replenish glycogen
• increased protein synthesis

e-
ATP
6
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
Heart muscle
14
acetyl-CoA

• FAs used for energy
• glucose, lactate, pyruvate,
• ketones (from blood) can
• be used

e-
ATP
7
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
14
Liver (high blood glucose)
acetyl-CoA

• glucose used to make
• glycogen and FAs
• biosynthetic paths may be
• stimulated

e-
ATP
8
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
Liver (low blood glucose)
6
14
acetyl-CoA

• FAs used for energy
• glycogen ? glucose
• AA catabolism supplies
• C for gluconeogenesis
• loss of CAC compounds
• may lead to ketone body
• production

17
ketone bodies
e-
ATP
9
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
(to blood)
aAAs
(from liver)
1
8
16
10
13
NADPH
NH4
3
aketo acids
ribose-5-P
2
11
7
15
lactate
urea
6
14
Adipose
acetyl-CoA

• low energy demand
• glucose used for energy
• stores FAs from liver as TAG
• releases FAs from stored TAG when needed

e-
ATP
10
dietary CHOs
dietary TAG
stored TAG (adipose)
dietary proteins
9
12
5
FAs
glucose
FAs
4
aAAs
1
8
16
10
13
NADPH
NH4
3
aketo acids
11
ribose-5-P
2
7
15
Ketogenic metabolism
lactate
urea
6
14
Liver
acetyl-CoA

• FAs used for energy
• glycogen depleted
• AA catabolism supplies
• C for gluconeogenesis
• loss of CAC compounds
• leads to ketone body
• production

17
ketone bodies
to blood
(fuel for brain other tissues)
in starvation, diabetes, low-carb diet
e-
ATP