Glycolytic pathway and enzymes

Fermentative Glucose Metabolism

Enzymes exclusive to Glycolysis

Enzymes Shared between the two pathways

Enzymes exclusive to gluconeogenesis

Follow the links on the enzyme name to learn more about its chemistry and its catalytic mechanism. There are also some rationales about how the pathways fit together, which reactions are the same and which must be different to maintain favorable standard free energies for both overall pathways
Glycolysis Pathway		.	Gluconeogenesis Pathway
	Glucose			.
	ATP → Hexokinase ADP ←	↓ ↑	→ P_i Glucose-6-Phosphatase
.	Glucose-6-Phosphate			.
Phosphoglucose Isomerase			.
.	Fructose-6-Phosphate			.
	ATP → Phosphofructokinase ADP ←	↓ ↑	→ P_i Fructose-1,6-Bisphosphatase
.	Fructose-1,6-Bisphophate			.
Fructose 1,6 bisphosphate aldolase			.
		DiHydroxyAcetone Phosphate AND Glyceraldehyde-3-Phosphate
Triose Phosphate Isomerase

NAD⁺ + P_i→ Glyceraldehyde-3-Phosphate Dehydrogenase NADH ←			.
.	1,3BisphosphoGlycerate			.
	ADP → Phosphoglycerate Kinase ATP ←		.
.	3 PhosphoGlycerate			.
Phosphoglycerate Mutase			.
.	2-PhosphoGlycerate			.
	enolase		.
. .	PhosphoEnolPyruvate			.
..	.	.		→ CO₂ + GDP (ADP equivalent) PEP carboxykinase ← GTP (ATP equivalent)
Compare the glycolysis, uncatalyzed and gluconeogenesis reactions side by side	ADP → Pyruvate Kinase ATP ←	↓	oxaloacetate 4 Carbon compound
.	.	.		→ADP + P_i pyruvate carboxylase ← CO₂ + ATP
.				.
---glycolysis "officially" ends here, but 1 of the 3 step below are required!--------------------------------------------------------------------------------------------------
pyruvate decarboxylase Ethanol fermentation: Beers, Wines The CO₂ released is used to raise bread		.		lactate dehydrogenase Lactate fermentation:(overworked muscle cells, red blood cells, yogurt making (Lactobacillus acidophilus))
.				.
pyruvate dehydrogenase This is NOT used in fermentative processes! This takes place in mitochondria and MUST lead to oxidative glucose metabolism.				.
.	.	.	.	.

Notes:

The part of the molecule that changes from the previous step is always colored red.
In two molecules, Dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G-3-P), a carbon is colored blue. This is the carbon that is the "same one" when DHAP is converted to G-3-P. NOTE: only G-3-P continues through glycolysis.
From G-3-P down in glycolysis, there are two molecules for each glucose that started. Conversly, starting at the bottom and goin "up" to G-3-P in gluconeogenesis, it takes to of each to generate one glucose.
glycolysis is shown on the left - gluconeogenesis is shown on the right.
- The process of glycolysis and gluconeogenesis share several reaction in common
- the reactions that are shared are denoted with the symbol. As these reaction proceed in EITHER direction (depending on the ΔG... more on this in two pages)
- only one enzyme is listed for these steps since the SAME enzyme is shared in BOTH diretions
- Some reactions, however, have a LARGE ΔG^o' value. These reactions are denoted with
- in These cases the pathways do NOT share this enzyme, and one is listed for each pathway.
in places where the arrows are not vertical... this simply denotes where one pathway uses two reactions while the other pathway utilizes only a single reaction