Glycolysis

stage 1

energy investment stage

reactions 1-4

stage 2

energy return

reactions 5-10

step 1

glucose to glucose-6-P

step 1 enzyme

hexokinase (glucokinase)

step 1 details

transferase, far from equilibrium, not reversible under cellular conditions, ATP consumed, transfer of a phosphate group

step 2

glucose-6-P to fructose-6-P

step 2 enzyme

phosphoglucoisomerase

step 2 details

isomerase, near equilibrium, reversible under cellular conditions depending on G6P and F6P (six ring to 5 ring)

step 3

fructose-6-P to fructose-1,6-BP

step 3 enzyme

phosphofructokinase-1

step 3 details

transferase, far form equilibrium, not reversible under cellular conditions, kinase, 2nd and last energy investiture of glycolysis, uses ATP

step 4

fructose-1,6-BP to glyceraldehyde-3-P and dihydroxyacetone-P

step 4 enzyme

aldolase

step 4 details

near equilibrium under cellular conditions, hydrolase, DHAP and GAP quickly pulled away so Q is less than 1

step 5

dihydroxyacetone-P to glyceraldehyde-3-P

step 5 enzyme

triose phosphate isomerase

step 5 details

ketose to aldose isomerization, near equilibrium, easily reversible under cellular conditions, have a enediol intermediate

-at the end of this step, 2 FAP molecules move through the rest of glycolysis

step 6

glyceraldehyde-3-P to 1,3-bisphosphoglycerate

step 6 enzyme

glyceraldehyde-3-P dehydrogenase

step 6 details

no ATP consumed, inorganic phosphate is utilized, another phosphoryl transfer reaction, NAD+ is a cofactor and first time NADH + H+ is produced, near equilibrium reaction

step 7

1,3-bisphosphoglycerate to 3-phosphoglycerate

step 7 enzyme

phosphoglycerate kinase

step 7 details

named for reverse reaction, near equilibrium, group transfer, first of 2 substrate level phosphorylations, ATP made (2X one for each molecule)

step 8

3-phosphoglycerate to 2-phosphoglycerate

step 8 enzyme

phosphoglycerate mutase

step 8 details

near equilibrium reaction, mutases function like isomerase except the phosphate that ends up on C-2 is not the same one that came from C-3

step 9

2-phosphoglycerate to phosphoenolpyruvate

step 9 enzyme

enolase

step 9 details

near equilibrium reaction, belongs to a class of enzymes called lyases (makes or breaks double bonds through removal of water), removes water molecule

step 10

phosphoenolpyruvate to pyruvate

step 10 enzyme

pyruvate kinase

step 10 details

far from equilibrium reaction, transferase, kinase, free energy of PEP hydrolysis is conserved in the synthesis of ATP in our second and last substrate level phosphorylation (2 ATP made, one for each molecule)

homolactic fermentation

pyruvate to lactate

homolactic fermentation enzyme

lactate dehydrogenase

alcoholic fermentation

pyruvate to acetaldehyde to ethanol

alcoholic fermentation enzyme

1) pyruvate decarboxylase

2) alcohol dehydrogenase