Glycolysis Steps -DMLT Final year

Glycolysis is the metabolic process that serves as the foundation for both aerobic and anaerobic cellular respiration. In glycolysis, glucose is converted into pyruvate

Step 1: Hexokinase

The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. The enzyme that catalyzes this reaction is hexokinase. In this step 1 molecule of ATP has been consumed.

Step 2: Phosphoglucose Isomerase

The second reaction of glycolysis is the rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) by glucose phosphate isomerase (Phosphoglucose Isomerase). this reaction involves an isomerization reaction.

Step 3: Phosphofructokinase

Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1,6 -bisphosphate. The enzyme that catalyzes this reaction is phosphofructokinase (PFK).

Step 4: Aldolase

The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate  (DHAP) and glyceraldehyde 3-phosphate (GAP).

Step 5: Triphosphate isomerase

The enzyme triophosphate isomerase rapidly inter- converts the molecules dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). Glyceraldehyde phosphate is removed / used in next step of Glycolysis.

Step 6: Glyceraldehyde-3-phosphate Dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate. The enzyme that catalyzes this reaction is glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

 

Step 7: Phosphoglycerate Kinase

Phosphoglycerate kinase transfers a phosphate group from 1,3-bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate. by the enzyme phosphoglycerate kinase (PGK). we actually synthesize two molecules of ATP at this step.

Step 8: Phosphoglycerate Mutase

The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate.

Step 9: Enolase

The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).

Step 10: Pyruvate Kinase

The enzyme pyruvate kinase transfers a P from phosphor-enol-pyruvate (PEP) to ADP to form pyruvic acid and ATP Result in step 10. we actually generate 2 ATP molecules.

Steps 1 and 3 = – 2ATP
Steps 7 and 10 = + 4 ATP
Net “visible” ATP produced = 2