Pentose Phosphate Shunt (aka Hexose Monophosphate Shunt)
- What are the two portions of this pathway?
- Oxidative
- Know oxidation steps.
- What is the net result of this portion?
- Is this portion reversible?
- Sugar interconversions
- Why are these reactions needed?
- Is it always necessary to run the two parts are the same rate? (i.e. do three G-6-P's always give two F-6-P's and a Ga-3-P?)
- Know flow diagram.
- What is the net result of this portion?
- When might these reactions be run backwards?
- In which tissues are the different portions elaborated?
- Which intermediates are common to glycolysis and pentose-P?
- How can this pathway be used to completely oxidize glucose?
- How is pentose-P controlled?
- How does control integrate it to biosynthesis?
- Example: Assume that 40% of the reducing equivalents used in fatty acid biosynthesis come from the HMP Shunt:
- If a cell makes fatty acid requiring a total of 550 reduction reactions, how many glucose molecules will be run through G-6-P DH? KEY
- Example: Assume that 50% of the reducing equivalents used in fatty acid biosynthesis come from the HMP Shunt and that each acetyl-CoA from glycolysis provides two C's for fatty acid biosynthesis:
- How many glucose molecules are needed to add 12 carbons to a fatty acid, assuming maximum incorporation into fatty acids? KEY
- Be familiar with detailed mechanisms for:
- Transketolase
- Given the substrates and catalysts,
- What cofactor is needed?
- be able to explain their mechanisms in catalytic terms,
- be able to show reasonable electron movements for bond making/breaking, including the structure of the chemically active ring of the catalyst.
KEY
- Be able to correlate the chemical mechanism with kinetic mechanism.
- Transaldolase (Note that the mechanism is the same as for aldolase, so you don't need to learn a new mechanism, just insert new substrates and follow to new products!)
- Given the substrates and catalysts,
- be able to explain their mechanisms in catalytic terms,
- be able to show reasonable electron movements for bond making/breaking. KEY
©R A Paselk
Last modified 9 December 2008
