Metabolic Biochemistry

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Metabolic Biochemistry Lecture 9 August 19,
2005 Oxidative phosphorylation Other Pathways of
Carbohydrate Metabolism Photosynthesis
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Import of NADH into mitochondria
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Example of a shuttle for oxidizing NADH from the
cytosol
LNC 19-27
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LNC 19-26
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Getting ATP and ADP in and out of mitochondria
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Biological work
LNC 19-25
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for NADH P/O ratio 2.5 for succinate
P/O ratio 1.5
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SUBSTRATE LEVEL PHOSPHORYLATION GAP Pi
NAD NADH 1,3
bisphosphoglycerate 1,3 bisphosphoglycerate
ADP ATP 3
phosphoglycerate 1 ATP produced per NAD
reduced per GAP used up per 3-PG produced
There is a precise stoichiometry
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OXIDATIVE PHOSPHORYLATION NADH 1/2 O2 H
NAD H2O 3 ADP
3 Pi 3ATP lt3 ATP produced per NADH
oxidized per H2O produced per 1/2 O2
consumed (P/O ratio 2.5)
There is no precise stoichiometry, because
protons can find other paths to return to the
matrix
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When succinate is the substrate, the P/O ratio is
1.5, because only two pumps are used (only 6
protons are pumped per succinate)
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Regulation of OXPHOS
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Mitochondria contain DNA (16.5 kb)
mtDNA encodes 2 rRNAs 22 tRNAs 13 proteins (in
animals)
mtDNA can have mutations causing mitochondrial
diseases
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GLUCONEOGENESIS LNC Chapter 14, Section
14.4 PENTOSE PHOSPHATE SHUNT LNC Chapter 14,
Section 14.5
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LNC Fig. 14-15
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phosphatase
third bypass
phosphatase
second bypass
fructose-1,6 bisphosphate
Phosphoenolpyruvate PEP
first bypass
pyruvate
LNC Fig. 14-16
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BIOTIN is a co-factor utilized for CARBOXYLATION
REACTIONS
THIAMINE PYROPHOSPHATE (TPP) is a co-factor
utilized for DECARBOXYLATION REACTIONS
LNC Fig. 14-18
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first bypass
in liver
in muscle
LNC Fig. 14-19
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Chapter 15, Section 15.3 (pp.575)
Coordinated Regulation of Glycolysis and
Gluconeogenesis
emphasis on regulation of phosphofructokinase-1
and fructose 1,6 bisphosphatase
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LNC Fig. 14-16
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Phosphofructokinase-1 4 identical subunits (two
shown) 1 active site per subunit 1 site for
allosteric regulator (ADP/ATP)
LNC Fig. 15.18
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Phosphofructokinase-1 PFK-1
Fructose bis-phosphatase FBPase
LNC Fig. 15-22
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LNC Fig. 15-23
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THE PENTOSE PHOSPHATE PATHWAY Section 14.5
two significant products ribose-phosphate NA
DPH
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End of Lecture 9 August 19, 2005