Bob's 4 Flashcards
How do you allosterically regulate enzymes?
Have a regulatory molecule bind the regulatory site and activate or inhibit the enzyme.
Covalently modify the enzyme by adding a phosphate group through protein kinase or dephosphorylate through protein phosphatase etc
What enzymes can be regulated in a metabolic pathway?
The irreversible ones can the irreversible ones cant be regulated effectively. Even if you inhibit them they will still come to equilibrium.
What is product inhibition?
Large amount of product pushes equilibrium back towards substrate eg large amount of c prevent B from going to C.
Can work further down as well known as feedback inhibition. Large amount of E prevents catalysis of D prevents C etc
Committing step regulation
Inhibit the committing step and intermediates can move down other pathways eg phosphofructokinase in glycolysis leads intermediates down pentose phosphate pathway
Catabolic pathway regulation
Inhibited by high energy signals like ATP and NADH and activated by low energy signals like ADP and NAD+
What is feed forward regulation?
Substrate early in pathway activates enzymes further down pathway- prepare for metabolites eg fructose 2-6 bisphosphate
Phosphoregulation examples?
Adrenaline- leads t phosphorylation of glycogen phosphorylase and so glycogen breakdown
Insulin- lead to dephosphorylation of glycogen phosphorylase and inhibits glycogen breakdown
Also insulin dephosphorylates and in turn activates pyruvate dehydrogenase which leads to the utilisation of glucose.
Why is phosphofructokinase a key regulator in glycolysis?
Irreversible step. Allosterically regulated in muscle. Stimulated by high AMP and inhibited by high ATP.
Hormonally regulated in liver.
Stimulated by insulin and inhibited by glucagon
Also stimulated by fructose 2,6 bisphosphate
Inhibited by PEP, citrate and H+
What inhibit step 6 of glycolysis?
High NADH or low NAD+
How is pyruvate kinase regulated?
Also by insulin and glucagon
How is hexokinase regulated?
By glucose-6-phosphate
Product inhibition
What is the committing step in glycolysis?
Phosphofructokinase
