LECTURE 11 - CATAPLEROTIC ANAPLEROTIC REACTIONS Flashcards
what is the CAC flux responsive to?
- energy state of the cell, through allosteric activation by ADP
- redox state of the cell, through the mitochondrial NADH/NAD ratio
- availability of energy rich compounds (acetyl CoA, succinyl CoA) that inhibit CAC enzymes (CS and alpha KGDH)
what are the cataplerotic reactions of the CAC used for?
- glucose biosynthesis
- fatty acid biosynthesis
- amino acid biosynthesis
how does glucose biosynthesis start from the CAC?
- starts with oxaloacetate
- it cannot exit the mitochondria as is, so it is converted to aspartate by transamination
- goes back to oxaloacetate once out of the mitochondria
- decarboxylated to make pyruvate
- can the be used to make glucose
what happens when you cannot store the extra amino acids?
too much nitrogen
asparate: the amino group can be taken off to make oxaloacetate, which is then used for energy in the CAC
what are some transamination pairs?
glutamate and alpha ketoglutarate
asparate and oxaloacetate
alanine and pyruvate
what does fatty acid biosynthesis start with?
need acetyl CoA, and then turn it into citrate
what is a reaction that replenishes oxaloacetate?
pyruvate + ATP -> oxaloacetate + ADP
a carbon is added to make a 4C compound
the enzyme is pyruvate carboxylase
what is the reaction that replenishes malate?
pyruvate + HCO3-+NADPH+H+–> L-malate + NADP+H2O
the enzyme is malic enzyme
carbon is added onto pyruvate to make malate
malate is also a source of NADPH for fatty acid synthesis if you do the reverse reaction
what is what one of the main transamination reactions in our body?
alpha ketoglutarate to glutamate
how can glutamate be made onto alpha ketoglutarate?
the enzyme is glutamate dehydrogenase
ADP activates and ATP deactivates
also releases NH4+
unfavorable in the reverse reaction because the enzyme has low affinity for ammonia, and you need almost toxic levels of ammonia for it to work
