Gluconeogenesis Flashcards
GNG enzymes that bypass Glycolysis
1) F16BP1 (F16BP–>F6P)
2) G6Pase (G6P–>G)
G6Pase opposes
hexokinase
F16BPase 1 opposes
PFK 1
Third enzyme that bypasses Glycolysis
Pyr–>PEP; 2 enzymes
1) pyruvate caboxylase
2) PEP carboxykinase
Intermediate: oxaloacetate
PFK2
bypasses PFK1
insulin can turn this on
glucagon turns this off
GNG substrates
lactate, pyruvate, glycerol, amino acids, any TCA intermediate
Pyruvate carboxylase requires
ATP, biotin, and CO2
PEP carboxykinase recyles energy by
regenerating DHAP and G3P
GNG energy source
Fatty acids
no beta-oxidation means no GNG
No beta-ox/no GNG
pt becomes hypoglycemic
MCAD
MCAD
medium chain acylcoA deficiency (no fat=no energy)
Cori cycle
recycles lactate–>lactic acidosis and change in body pH
lactate–>pyr–>glucose (GNG in the liver)
Liver in GNG
function is to provide glucose for extra-hepatic tissues has a high Km glucokinase to regulate blood glucose
Muscle in GNG
a ready source of metabolic fuel; uses slp to provide ATP from creatine and glycolysis
has no G6Pase so can’t break glycogen into glucose for the body
Glycogenolysis
inhibited by insulin and stimulated by cAMP
Glycogenesis
stimulated by insulin and inhibited by cAMP
Glycogenesis enzymes
branching enzyme, glycogen synthase
Glycogenolysis enzymes
debranching enzyme, glycogen phosphorylase
Glycogen structure
glycogenin in the middle and glycogen subunits surround it
High blood glucose
insulin tells body to make glycogen/no more glucose
Low blood glucose
glucagon tells body to break down glycogen/need more glucose
