Biological Inorganic Chemistry
Oxygen consumption
Formation of carbon dioxide
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Bioinorganic Chemistry BIC5
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C6H12O6 + 6O2  6CO2 + 6H2O
• Glycolysis in the cytosol (the degradation
to puruvate)
• Cit
Citric
i acid
id cycle
l iin th
the mitochondria
it h d i
(tricarboxylic acid cycle)
• Oxidative phosphorylation (electron
transport chain)
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Bioinorganic Chemistry BIC5
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Fig. 14.2 a and b
Lehninger
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Bioinorganic Chemistry BIC5
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1
Glycolysis 1
1
Hexokinase
Mg 2+
+ H+
2
Ph
Phosphoglucose
h l
iisomerase
Mg 2+
Phosphofructo kinase
3
Mg 2+
+ H+
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Glycolysis 1
Mg2+ dependence
log K MgATP2- = 4.34
log K MgADP- = 3.22
:
2ATP spent, 2 ADP formed
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Bioinorganic Chemistry BIC5
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Glycolysis 2
4
Aldolase
Triosephosphate
isomerase
5
Glyceraldehyde-3phosphatedehydrogenase
h
h t d h d
2 ti
times
NAD++ HPO42-
NADH + H+
6
Phospoglycerate kinase
2 times
MgADP-
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MgATP2-
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2
Glycolysis 1 and 2
+ 2 MgATP2- + 2 NAD+ + 2 MgADP- + 2 HPO42give
2
+ 2 MgATP2- + 2 NADH + 2 MgADP- + 4 H+
Essentially:
loss of 2 NAD+
cleavage of glucose to 2 trioses
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Glycolysis 3
7
phosphoglycerate
mutase
3-phosphoglycerate
→2+ 2-phosphoglycerate
Mg
8
→
+ H2O
enolase
l
+ MgATP2-
pyruvate kinase
9
+ MgADP- + H+→
10
↔
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tautomerisation (keto-form more
stable)
Bioinorganic Chemistry BIC5
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Glycolysis 3
2 phosphoglycerate + 2 MgADP- + 2 H+ →
2 pyruvate + 2 MgATP2Essentially:
gain of 2 ATP
rearrangement: triose to pyruvate
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3
Glycolysis 1 + 2 + 3
+ 2 MgATP2- + 2 NAD+ + 4 MgADP- + 2 HPO42- + 2H+
g
give
+ 4 MgATP2- + 2 NADH + 2 MgADP- + 2H2O + 4H+
2
Essentially : gain of 2 ATP and
loss of 2 NAD+
cleavage of glucose to 2 pyruvate
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From cytosol to mitochondria
Cytosol:
+ 2 NAD+ + 2 MgADP- + 2 HPO42- →
+ 2 MgATP2- + 2 NADH + 2H2O + 2H+
2
NAD+
NADH
Pyruvate + CoA-SH
Acetyl-coenzyme A + CO2
Acetyl-coenzyme A is taken into the mitochondria
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Coenzyme A
NAD+
NADH
CO2
CH2 – CH2 CH3-C- S
O
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: CH3CO-S-CoA
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4
Lehninger
•
•
•
•
•
Fig. 16-7
Fig. 16.10
Fig. 19.5
Fig. 16.11 (First oxidative decarboxylation)
Fig 19.10
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Glycolysis + Citric acid cycle
C6H12O6 gives six CO2 (and 2ATP+ 2GTP)
reducing 12 NAD+ (or similar) to NADH.
Reoxidation
R
id ti iis affected
ff t d b
by th
the electron
l t
transport chain
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Lehninger
•
•
•
•
Electron transport chain Table 19.3
Fig. 19.9 cytochrome c reductase
Fig. 19.11
Fig. 19.12
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5
Cytochrome c oxidase
Lehninger Fig. 19-14
4-electron reduction
path – haem a3 – CuB
Summary Fig 19-16
Cytochrome c
Prostetic group haem c :
Cysteine thiols added to haem b
-CH=CH2 + R-SH
→-(R-S)CH-CH3
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6