CHEM430: Glycolysis

Glycolysis Reaction 1

Enzyme: hexokinase (glucokinase)

Substrate: glucose

Product: Glucose-6-P (G6P)

*consumes ATP (net -1 ATP thus far)

*far from equilibrium

*transferase rxn

Glycolysis Reaction 2

Enzyme: phosphoglucoisomerase

Substrate: Glucose-6-P

Product: Fructose-6-P

*near equilibrium

*isomerization (rearrangement)

Glycolysis Reaction 3

Enzyme: phosphofructokinase-1 (PFK)

Substrate: Fructose-6-P

Product: Fructose-1,6-BP

*far from equilibrium

*transferase rxn

*ATP consumed

*committed step

Glycolysis Reaction 4

Enzyme: Aldose

Substrate: fructose-1,6-BP

Product: glyceraldehyde-3-P AND dihydroxyacetone-P

*near equilibrium under cellular conditions

*hydrolase rxn

Glycolysis Reaction 5

Enzyme: triose phosphate isomerase

Substrate: dihydroxyacetone-P (DHAP)

Product: glyceraldehyde-3-P (GAP)

*near equilibrium

*ketose to aldose isomerization rxn

*at the end of this step, 2 GAP molecules move to stage II

Glycolysis Reaction 6

Enzyme: Glyceraldehyde-3-P dehydrogenase

Substrate: Glyceraldehyde-3-P

Product: bisphosphoglycerate

***NAD+ --> NADH + H+ (REDOX!!)

*adds phosphate from environment (not from ATP)

*near equilibrium

Glycolysis Reaction 7

Enzyme: phosphoglycerate kinase

Substrate: 1,3-bisphosphoglycerate

Product: 3-phosphoglycerate, ATP

***substrate-level phosphorylation

*near equlibrium

*transferase rxn

Glycolysis Reaction 8

Enzyme: phosphoglycerate mutase

Substrate: 3-phosphoglycerate

Product: 2-phosphoglycerate

*near equilibrium

*mutases function like isomerases except the phosphate that ends up on C2 is not the same one that came from C3

*2,3-BPG is an intermediate, and some is shunted off and interacts with Hb

Glycolysis Reaction 9

Enzyme: enolase

Substrate: 2-phosphoglycerate

Product: phosphoenolpyruvate (high energy molecule!)

*dehydration reaction

*near equilibrium

Glycolysis Reaction 10

Enzyme: pyruvate kinase

Substrate: phosphoenolpyruvate

Product: pyruvate, ATP

***substrate level phosphorylation

*far from equilibrium (due to tautomerization of pyruvate, the energy of the product is much lower than the substrate)

homolactic fermentation

Enzyme: lactate dehydrogenase

Substrate: pyruvate, NADH

Product: lactate, NAD+ + H+ (oxidized)

Alcoholic fermentation

Enzymes: 1) pyruvate decarboxylase 2) alcohol dehydrogenase

Substrate: pyruvate, NADH

product: ethanol, NAD+ + H+ (oxidized)

Gluconeogenesis first reaction

gluco 2nd

gluco 3rd

gluco 4th

gluco 5th

gluco 6th

gluco 7th

gluco 8th

gluco 9th

gluco 10th

gluco 11th

net glucogenesis equation

bypass reactions for gluconeogenesis - reaction 1

bypass reactions for gluconeogenesis - reaction 10, 11

shared enzymes between glycolysis and gluconeogenesis

+ phosphoglucose isomerase