PENTOSE PHOSPHATE Pathway

1
PENTOSE PHOSPHATE Pathway

• Glucose-6-PO4 ? Ribose-5-PO4
• Synthesize NADPH for fatty acid synthesis
• Metabolize pentoses

Take Home The PENTOSE PHOSPHATE pathway is
basically used for the synthesis of NADPH and
D-ribose. It plays only a minor role (compared
to GLYCOLYSIS) in degradation for
ATP energy.
2
STAGE I
(Oxidation)
NADP
H2O
NADPH H
Lactonase
6-Phosphoglucono-?- lactone
6-Phospho- gluconate
Glucose-6-PO4
G-6-P dehydrogenase
3
Ribose-5-PO4
Ribulose-5-PO4 (Ru5P)
Ru5P isomerase
NADP
NADPH H
Ru5P epimerase
6-phosphogluconate dehydrogenase
6-Phosphogluconate
STAGE II
Xylulose-5-PO4
4
STAGE III

Xyulose-5-PO4
Ribose-5-PO4
Sedoheptulose-7-PO4
Transketolase
Glyceraldehyde-3-PO4
5

Glyceraldehyde-3-PO4
Fructose-6-PO4
Sedoheptulose-7-PO4
Transaldolase
Erythrose-4-PO4
6


Glyceraldehyde- 3-PO4
Xylulose-5-PO4
Erythrose-4-PO4
Fructose-6-PO4
Transketolase
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SUMMARY
TK
5 5 ?
3 7
TA
7 3 ? 4 6
TK
4 5 ? 3 6
Xylulose-5-PO4
Erythrose-4-PO4
Ribose-5-PO4
Fructose-6-PO4
Glyceraldehyde-3-PO4
Sedoheptulose-7-PO4
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18 carbons
3 Glucose-6-PO4 6 NADP 3H2O
3 carbons
12 carbons
6 NADPH 6H 3CO2 2 Fructose-6-PO4
3 carbons
Glyceraldehyde-3-PO4
18 3 12 3
Note that
1. For each glucose oxidized, 2 NADPHs are formed
2. Sedohepulose-7-PO4, erythrose-4-PO4 are
strictly intermediates
3. Fructose-6-PO4 is never used as an
intermediate
4. Glyceraldehyde-3-PO4 is both an intermediate
and final product
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The Dangers of Primaquine
Hemolytic anemia
Glutathione
NADPH
Reduced hemoglobin and cell lysis
G-6-P dehydrogenase
See p 423 in Textbook
Glutathione reductase