Glycolysis, Gluconeogenesis, and thePentose Phosphate Pathway

Part 2: Gluconeogenesis and PPP

Chapter 14

Gluconeogenesis and PPP Learning Goals.

Know:

1. Entry to gluconeogenesis.

2. Glycolysis backwards: which enzymes are at Eq and those that are the drivers.

3. What makes some amino acids glucogenic.

4. Pentose Phosphate Pathway entry by glucose-6-P and transaldolases, transketolases.

5. Why the PPP is a web pathway.

Gluconeogenesis Forms Sugars from Other Metabolites

Going Forwards and Backwards

The Beginning of Gluconeogenesis

Pyruvate Carboxylase

PEP Carboxykinase

Pyruvate Actually Has Two Ways to PEP

The End of Gluconeogenesis

Gluconeogenesis Energetics

EOC Problem 21: overall energetics of Glycolysis and Gluconeogenesis.

EOC Problem 22: Concept of a Futile Cycle.

Pentose Phosphate Pathway Beginning

+aromatic amino acids + His

SuperOxide Dismutase

NADPH and Oxygen Toxicity

PPP Beginning from Glucose-6-Phosphate

Lactonase

6-Phosphogluconate DH

Phosphopentose Isomerase (not an Epimerase)

Ribose-5-Phosphate Epimerase

PPP the Web like Pathway Stuck onto the Side of Glycolysis

PPP Transketolases transfer 2 Carbon units

PPP Transketolases transfer 2 Carbon units

PPP Transaldolases transfer 3 Carbon units

Another Transketolase

PPP Arranged to Oxidize Glucose (6 in and 5 out)

6 Glucose-6-P

Control of PPP by NADPH

PPP Functions:1. Produce Ribose-5-P for Nucleotide Synthesis

2. Produce Ribose-5-P for His Synthesis

3. Produce Erythrose-4P for Trp, Tyr, Phe Synthesis WYF

4. Can Completely Oxidize Glucose

5. Source of NADPH (Biosynthesis, Oxygen Killing System)

6. Can be Rearranged to Calvin Cycle – Fix CO2

7. Other Specialized Reasons (Heterofermenters, etc. mainly in prokaryotes)

Things to Know and Do Before Class

1. Entry to gluconeogenesis.

2. Glycolysis backwards: which enzymes are at Eq and those that are the drivers.

3. What makes some amino acids glucogenic.

4. Pentose Phosphate Pathway entry by glucose-6-P and transaldolases, transketolases.

5. Why the PPP is a web pathway.

6. EOC Problems: 21, 22, 25 – 27.