Glucose is an indispensable metabolite ● The brain requires at least ~50% of its calories in the...
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Transcript of Glucose is an indispensable metabolite ● The brain requires at least ~50% of its calories in the...
Glucose is an indispensable metabolite
● The brain requires at least ~50% of its calories in the form of glucose
● Red blood cells exclusively subsist on glucose
● Glucose is a precursor of other sugars needed in the biosynthesis of nucleotides, glycoproteins, and glycolipids
● Glucose is needed to replenish NADPH, which supplies reducing power for biosynthesis and detoxification
© Michael Palmer 2014
The pyruvate carboxylase reaction
© Michael Palmer 2014
The active site of E. coli biotin carboxylase
© Michael Palmer 2014
Activation of bicarbonate and carboxylation of biotin
© Michael Palmer 2014
The carboxylation of pyruvate
© Michael Palmer 2014
The phosphoenolpyruvate carboxykinase reaction
© Michael Palmer 2014
Fructose-1,6-bisphosphatase and glucose-6-phosphatase
© Michael Palmer 2014
Energy balance of gluconeogenesis
© Michael Palmer 2014
Mitochondrial substrate transport in gluconeogenesis
© Michael Palmer 2014
Ethanol degradation inhibits gluconeogenesis
© Michael Palmer 2014
Simultaneous activity of glycolysis and gluconeogenesis creates futile cycles
© Michael Palmer 2014
Glucose phosphorylation cycling involves two separate compartments
© Michael Palmer 2014
Allosteric regulation limits fructose-6-phosphate phosphorylationcycling
© Michael Palmer 2014
Hormonal control of phosphofructokinase andfructose-1,6-bisphosphatase
© Michael Palmer 2014
The secondary messengers cAMP and fructose-2,6-bisphosphate
© Michael Palmer 2014
Regulation of pyruvate kinase
● allosteric inhibition by ATP
● allosteric activation by alanine and fructose-1,6-bisphosphate
● inhibition by PKA-mediated phosphorylation