pathway regulation Flashcards
define Allostery
Activator/inhibitor binds another site
What kind of steps in a pathway tend to be regulated
Irreversible steps are potential sites regulation
reduced activity reduces the flux of substrates through the pathway directly
reducing levels of product
Why are reverse steps not Regulated
Even when inhibited reaction still comes to equilibrium similar levels of product are unaffected
Product inhibition feedback
inhibition in pathway of the final product which binds to the first enzyme in the pathway, reduces entry of substrate and builds up an intermediate in the pathway
What can inhibit catabolic pathways
High energy signals
ATP, NADH, FADH2
Catabolic pathways are Activated by low energy signals
ADP, AMP, NAD+, FAD
What is meant by hormonal regulation
Phosphorylation or de-phosphorylation target protein
hormone receptor binding
activate signal pathway
What enzyme Dephosphorylates
Protein phosphatase
How is hexokinase controlled
Metabolic regulation product inhibition by a buildup of glucose-6-phosphate.
Inhibition at step five due to hgh NADH although NAD+ results in a buildup of glycolytic intermediates downstream
What is the key regulatory enzyme in glycolysis
phosphofructose kinase one
How is phosphofructo kinase one regulated
Allosteric regulation
hormonal regulation
metabolic regulation
Describe phosphofructokinase 1 allosteric regulation
Inhibition by high ATP and other high level signals like citrate
stimulated by high AMP and other low signals like fructose 2 6 bis phosphate
Describe phosphofructosekinase 1 hormonal regulation
Stimulated by insulin activating protein phosphatase one which Dephosphorylates
Inhibits by glucagon activating protein kinase a which phosphorylates
Regulation of step five of glycolysis
Metabolic regulation
as the step makes NADH
if there is a high level of NADH or a low NAD+ causes product inhibition
Pyruvate kinase regulation
Hormonal
stimulatory insulin activates protein phosphatase one which leads to dephosphorylation
inhibitory glucagon activates protein kinase a which leads to a phosphorylation
