10 Reactions of Glycolysis

Answer the following for step 1 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Glucose + ATP

2. Glucose 6-Phosphate + ADP + H+

3. Hexokinase requires Mg 2+

4. Irreversible

5. Phosphoryl transfer

6. Energetically favorable

7. Coupled to hydrolysis of ATP

8. Substrate inhibition

9. Phosphate group transferred from ATP to C6 of glucose

Answer the following for step 2 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Glucose 6-phosphate

2. Fructose 6-phosphate

3. Phosphoglucose isomerase

4. Reversible

5. Isomerization

6. Energetically unfavorable

7. Not coupled to any other steps

8. Product concentration kept low to drive rxn forward

9. General base catalysis via Glu residue causes formation of cis-enediol intermediate followed by general acid catalysis of same Glu residue

Answer the following for step 3 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Fructose 6-phosphate + ATP

2. Fructose 1,6-bisphosphate + ADP + H+

3. Phosphofructokinase requires Mg2+

4. Irreversible

5. Phosphoryl transfer

6. Energetically favorable

7. Coupled to ATP hydrolysis

8. Regulated by ATP, fructose-2,6-bisphosphate, and other metabolites

9. Phosphate group transfers from ATP to C1 of Fructose 6-phosphate

Answer the following for step 4 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Fructose 1,6-bisphosphate

2. Dihydroxyacetone phosphate + Glyceraldehyde 3-phosphate

3. Aldolase

4. Reversible via Aldol Condensation

5. Aldol cleavage

6. Energetically unfavorable

7. Not coupled to any other steps

8. Glyceraldehyde 3-phosphate concentration kept low to pull reaction forward

9. Fructose 1,6-bisphosphate cleaved into to 3C sugars (C1-3) make up Dihydroxyacetone phosphate (DHAP) and (C4-6) make up Glyceraldehyde 3-phosphate (GAP)

Answer the following for step 5 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Dihydroxyacetone phosphate (DHAP)

2. Glyceraldehyde 3-phosphate (GAP)

3. Triose phosphate isomerase

4. Reversible

5. Isomerization

6. Energetically unfavorable

7. Not coupled to any other steps

8. GAP concentration kept low to pull rxn forward

9. Glu acts as a general base on C1 forming C=C. His residue acts as general acid on carbonyl of C2. His acts as a general base on C1(OH). Glu acts as a general acid on C2.

Answer the following for step 6 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Glyceraldehyde 3-phosphate (GAP) + Pi + NAD+

2. 1,3-bisphosphoglycerate + NADH + H+

3. Glyceraldehyde 3-phosphate dehydrogenase

4. Reversible

5. Phosphorylation coupled to oxidation

6. Energetically unfavorable

7. Coupled to step 7

8. Coupling to next reaction allows reaction to proceed

9. When NAD+ is bound to GAP, Cys residue forms covalent thiohemiacetal linkage. Oxidation by NAD+ forms NADH that leaves the active site. 2nd NAD+ and Pi are able to incorporate because thioester high energy bond is broken ending in release of 1,3-BPG as the product.

Answer the following for step 7 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. 1,3-Bisphosphoglycerate + ADP

2. 3-Phosphoglycerate + ATP

3. Phosphoglycerate kinase requires Mg2+

4. Reversible

5. Phosphoryl transfer

6. Energetically favorable

7. Coupled to step 6

8. Reversible due to coupling to step 6

9. 1,3-BPG is high energy compound capable of substrate-level phosphorylation to make ATP

Answer the following for step 8 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. 3-Phosphoglycerate

2. 2-Phosphoglycerate

3. Phosphoglycerate mutase uses Mg2+

4. Reversible reaction

5. Phosphoryl shift

6. Energetically unfavorable

7. Not coupled to any other steps

8. Reactant concentration kept high by PGK to push forward reaction

9. Phosphorylated His transfers phosphoryl group to C2 (OH). Second His residue acts as general base. Phosphoryl transfer from C-3 of the substrate to the first active-site His. The second His residue acts as a general acid catalyst.

Answer the following for step 9 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. 2-Phosphoglycerate

2. Phosphoenolpyruvate + H2O

3. Enolase

4. Reversible

5. Dehydration

6. Energetically unfavorable

7. Indirectly coupled to step 10

8. Product concentration kept low to pull rxn forward

9. Removal of OH from C3 and H from C2 lead to C=C formation and water

Answer the following for step 10 of glycolysis

1. What is the reactants?

2. What is the products?

3. What enzyme is used? Does its require any cofactors?

4. Is the reaction reversible?

5. What is the reaction type?

6. Is the reaction energetically favorable?

7. Is it coupled to any other steps?

8. If its regulated how so?

9. Explain the mechanism

1. Phosphoenolpyruvate (PEP) + ADP + H+

2. Pyruvate + ATP

3. Pyruvate kinase requires divalent metals (Mg2+ or Mn 2+) and K+

4. Irreversible

5. Phosphoryl transfer

6. Energetically favorable

7. Indirectly coupled to step 9

8. Regulated by ATP, divalent metals, and other metabolites

9. Substrate level phosphorylation with ADP makes ATP. Loss of phosphate from PEP yields enol that tautomerizes into ketone lowering concentration of product driving reaction forward.