1. Glycolysis
1. The Glycolytic Pathway 2. The Reactions of Glycolysis By: Mohammed Imran Anees Y.B.C.C.P Aurangabad

3. Glycolysis Glucose is converted to pyruvate while generating two ATPs.
2 molecules of NAD+
are converted to
2 molecules of NADH.
The oxidizing power of
NAD+ must be recycled.
Figure 16-1 Glycolysis overview

4. Pathway Overview
There are 10 enzyme-catalyzed reactions considered to occur in two stages
Stage I (reactions 1-5): Preparatory stage where glucose is phosphorylated and cleaved to yield 2 molecules of glyceraldehyde-3-phosphate (GAP). Stage I uses 2 ATPs.
Stage II (reactions 6-10) Payoff stage where 2 GAPs converted to pyruvate and generation of 4 ATPs.

5. The Reactions of Glycolysis Stage I (Preparatory Stage)
1. Hexokinase (first ATP utilization) 2. Phosphoglucose Isomerase (PGI) 3. Phosphofructokinase -1 (PFK-1) (second ATP utilization) 4. Aldolase 5. Triose Phosphate Isomerase (TIM)

6. THE PREPARATORY PHASE Step 1 – Hexokinase
Hoexokinase (first ATP utilization)

7. Step 2 – Phosphoglucose Isomerase (PGI) [Phosphohexose isomerase]
catalyzes the conversion of
G6P to F6P, the isomerization
of an aldose to a ketose.
Phosphoglucose Isomerase (PGI)

8. The isomerization of an aldose to a ketose

9. (C) Step 3 - Phosphofructokinase 1:
Second ATP utilization
Phosphofructokinase: Second ATP Utilization

10. D. Step 4 - Aldolase
Aldolase catalyzes cleavage of fructose-1,6-bisphosphate (FBP) in reaction 4 of glycolysis.
This forms two trioses
Glyceraldehyde-3-phosphate (GAP)
Dihydroxyacetone phosphate (DHAP).

11. Step 4 - Aldolase. Aldol cleavage of FBP to form two
Trioses (GAP and DHAP)
Note that the atom
numbering system
changes. Atoms 1, 2,
and 3 of glucose become
atoms 3,2, and 1 of
DHAP. Atoms 4, 5, and
6 become atoms
1, 2, and 3 of GAP.
Cleavage of FBP to form two trioses.

12. (E) Step 5 - Triose Phosphate Isomerase (TIM)
Only GAP continues
along the glycolytic
pathway.
TIM – the final reaction of Stage I.

13. Stage II - payoff phase
6. Glyceraldehyde-3-Phosphate Dehydrogenase (GAPDH) first "High-energy" intermediate formation.
7. Phosphoglycerate Kinase (PGK): First ATP Generation.
8. Phosphoglycerate Mutase (PGM).
9. Enolase: second "High-energy" intermediate formation.
10. Pyruvate Kinase (PK): Second ATP generation.

14. (F) Step 6 - Glyceraldehyde-3-Phosphate Dehydrogenase (GAPDH): First “High-Energy” Intermediate Formation.

15. (G). Step 7 - Phosphoglycerate Kinase (PGK): First ATP Generation.

16. Mechanism of the PGK reaction.
Figure The mechanism of the PGK reaction. The Mg2+ positions are shown as examples; their actual binding sites are unknown.

17. (H). Step 8 - Phosphoglycerate Mutase (PGM).

18. (I) Step 9 - Enolase: Second “High-Energy” Intermediate Formation
(I) Step 9 - Enolase: Second “High-Energy” Intermediate Formation. (Dehydration reaction)
Enolase

19. (J) Step 10 - Pyruvate Kinase (PK) : Second ATP Generation.

20. Thank you