1. GLYCOLYSIS AND ALTERNATIVES
BIOT 309
Fall 2013

2. GLYCOLYSIS AND ALTERNATIVES
Bacteria use 3 different pathways to convert glucose to PGA (3-phosphoglycerate) (see diagram)
Embden-Myerhoff (shown in next slide)
Entner-Dordoroff (ED) Pathway
Pentose phosphate pathway (shunt)/hexose monophosphate shunt
Energy yields are different.
What are they?

3. QUICK REVIEW EMP GLYCOLYSIS

4. ENTNER-DUODOROFF PATHWAY
Uses EMP pathway for some steps
Unique enzymes and intermediates

5. ED PATHWAY*
* Be aware that this figure does not show ATP use or production since enzymes from EMP pathway perform these reactions.

6. ED PATHWAY * From G6P to KDG split enzymes are * * * * * < - - -
Glucose begins pathway
E yield = 1 ATP + 1 NADH + 1 NADPH
* From G6P to KDG split enzymes are
different
Pyruvate formation
Directly 
Indirectly – G3P enters EMP < - - * *
< - - - * *  *

7. Entner Duodoroff Pathway What do abbreviations stand for?
MAKE a list!!!

8. SIDE-BY-SIDE COMPARISON
From G6P to
KDG/KDPA split into G3P + pyruvate enzymes different

9. THIRD GLYCOLYSIS PATHWAY
Pentose Phosphate Pathway (PPP) =
Hexose Monophosphate Pathway (HMP) =
Phosphogluconate Pathway
Sometimes called a shunt.
Operates at same time as EMP

10. It’s a shunt

11. PPP is a shunt
The pathway begins with the glycolytic intermediate glucose 6-P.
It reconnects with glycolysis because two of the end products of the PPP are glyceraldehyde 3-P and fructose 6-P; two intermediates further down in the glycolytic pathway.
It is for this reason that the PPP is often referred to as a shunt.

12. PPP
Provides ribose-5-phosphate = precursor to ribose and deoxyribose in nucleic acids
Provides erythrose phosphate = precursor for synthesis of aromatic amino acids
Other intermediates used in other pathways
Provides NADPH – major source of energy for anabolic reactions, e.g., nucleic acids, lipids
Used exclusively by Thiobacillus novellus and Brucella abortus

13. PATHWAY INTERMEDIATE USES

14. High [NADPH] inhibits allosterically
1st Reaction
High [NADPH] inhibits allosterically
High [NADP+] stimulates allosterically
irreversible
irreversible

15. MAKES SUGARS WITH DIFFERENT CARBON NUMBERS
All reversible
Transketolase 1
2 5C 1 7C + 1 3C
2 enzymes convert ribuloe-5-Pi to a ketose and an aldose both with 5 C
Transketolase 2
1 7C +1 3C  4C+6C
Transketolase 3
4C+5C  6C + 3C

16. Transketolase
Requires thiamine diphosphate (TDP) and Mn2+ as co-factors
TDP (TPP) is needed for redox

17. Regulation G-6-P is partitioned between EMP and PPP Depends on
NADP+ and NADPH concentrations
NADP+ high favors EMP
NADPH high favors PPP

18. ENTNER-DUDOROFF PATHWAY
The Entner-Doudoroff pathway yields one ATP and two NADPH molecules from one glucose molecule.
Uses 4 enzymes that are different from EMP
1 Glucose pyruvate + 1 ATP + 1 NADH
+ 1 NADPH
Bacteria: Pseudomonas, Rhizobium, Azotobacter, Agrobacterium, Enterococcus faecalis

19. PENTOSE PHOSPHATE SHUNT PATHWAY
Precursors to the ribose and deoxyribose in nucleic acids
Provides erythrose phosphate which is a precursor for synthesis of aromatic amino acids
reducing power = NADPH
Overall Oxidative Reaction: 1 Glucose 6 – P + 2 NADP H2O 
1 Ribose 5-P + 1 CO2+ 2 NADPH + 2 H+
Non-Oxidative Reactions
change number of carbons in sugar molecules
make intermediates used in other biosynthetic pathways including feeding back into PPP and EMP
Used exclusively by Thiobacillus novellus and Brucella abortus

21. Additional Topics

22. Coenzyme A
CoASH
Free SH
role in TCA
alpha KG -> succinyl CoA

23. Coenzyme A = acyl group carrier, donates acyl group to other molecules
Acetyl = acetyl CoA
Succinyl = succinyl CoA
Roles in
Oxidation of pyruvate in TCA
Synthesis and oxidation of fatty acids

24. Acetyl Coenzyme A Structure*
* What is this? Vitamin B5

25. END