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GLYCOLYSIS

- carbohydrates are the most abundant macromolecules
- 1 mole of glucose can release 2840Kj
- When glucose is not needed it is easy for our cells to store it in polymeric forms: glycogen & starch
Ways to store glucose
1
...
Energy production by oxygenation of glucose
3
...
Structure carbohydrate production [cell walls of fungi and bacteria]
Step 1: phosphorylation of glucose
From Glucose to Glucose 6 phosphate
- enzyme: hexokinase
- ΔG’°= -16
...
7 Kj/mol
- G6P is asymmetric so F6P will be easier to phosphorylate by
PFK1, allowing symmetrical cleavage by aldolase: cleavage of
step 3 happens between alpha carbon and beta carbon: carbonyl
C1 in glucose would be C2/C3 while in fructose [which is a
ketone] carbonyl carbine is on C2 so the C3/C4 which are
isomers when they’re cut
...
8Kj/mol
- Dihydroxyacetone is a ketone: C1 of F1,6BP
...
5Kj/mol
PREPARATORY PHASE IS FINISHED
Step 6: oxidation of GAP
From glyceraldehyde3-P to 1,3-biphosphoglycerate
- enzyme: glyceraldehyde 3- phosphate dehydrogenase
- ΔG= 6
...
Oxidative process: aldehyde group of GAP
presence of inorganic P gives a carboxylic group
2
...
5 ATP)
- in 1,3-biphosphoglycerate the P group has a lot of energy and is attached though a anhydrate bond
- The other P on C3 doesn’t have energy and it’s linked by phosphoester bond

Step 7: first production of ATP
From 1,3 biphosphoglycerate to 3-phosphoglycerate
- enzyme: phosphoglycerate kinase
- ΔG= -18
...
Carboxyl group at the end can not be oxidised
2
...
Ester bond has no much energy

Step 8: migration of the phosphate
From 3-phosphoglycerate to 2 phosphoglycerate
- enzyme: phosphoglycerate mutase
- ΔG’°= 4
...
5Kj/mol
- Generate a high energy phosphate compound: 2phosphoglycerate is not good enough since it has 2
negative charges too close to each other
- Remove water from 2 adjacent C atoms= formation of
double bond, C2 will adopt all sp2 conformation
- Overlapping of negative charges will give to the energy
source the ability to rebuild another ATP
Step 10: 2nd production of ATP
From PEP to pyruvate
- enzyme: pyruvate
- ΔG’°= -31 Kj/mol [higest thermodynamically
favourable]
- Substrate level phosphorylation to make ATP (x2)

Loss of P from PEP yields to an enrol that TAUTOMERIZES into ketone: effectively lower the concentration
of reaction products and drives reaction towards ATP formation
Summary of glyclosis
Used

1 glucose, 2 ATP
...
Endogenous glycogen: phosphorylase —>
2
...
Glucose 6-phosphate [identical to the one made out of pure glucose]
Fates of pyruvate
Aerobic conditions
- expulsion 2CO2
- 2 acetyl-coA: citric acid cycle
- 4CO2 + 4H2O

acetyl coA is first molecule entering Krebbs cycle
it is a CH3COS thioester: pyruvate has 3 carbons
conversion catalysed by pyruvate dehydrogenase
with release of 2CO2

Anaerobic conditions: deoxidation of NADH+ H+ into NAD+ : fermentation
a) Lactic acid fermentation
From kept group of pyruvate, alcohol group in lactate [reduction, oxidation of NADH H+]
- the acidification prevents strenuous work of muscle, takes place when it is contracting
- Athlete avoid it by giving to the muscle an enough supply of O
- Enzyme: lactate dehydrogenase
...
This oxidation is really important because without NAD+
glycolysis could not take place

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