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,
- be able to explain their mechanisms in catalytic terms,
- be able to show reasonable electron movements for bond making/breaking
- 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.
©R A Paselk
Last modified 3 April 2013
