Control of metabolism

Question 1

What are the three steps of regulatory mechanisms

Answer 1

Non covalent interactions
Covalent interactions
Changes in abundance of the enzyme

Question 2

What is allosteric regulations and what does it do?

Answer 2

It is the binding of allosteric effectors at allosteric sites.
It affects catalytic efficiency of the enzyme (I.e phosphofructose kinase)

Question 3

What’s the difference between non regulatory enzymes and regulatory enzymes?

Answer 3

Non regulatory enzymes exhibit hyperbolic interactions
Regulatory enzymes exhibit sigmoidal kinetics

Question 4

Differences between Allosteric activators and allosteric inhibitors

Answer 4

Allosteric activators
Decrease in Km ( increases enzyme binding affinity)
Increase in Vmax ( increases enzyme catalytic efficiency)

Allosteric inhibitors
Increase in Km ( decrease in enzyme binding affinity)
Decrease Vmax ( decrease in enzyme catalytic efficiency)

Question 5

What is phosphofructose kinase allosterically inhibited by? What does this mean?

Answer 5

High levels of ATP ( Amp reverses the action of ATP)
This means enzyme activity increases when the ATP/AMP ratio is lowered

Question 6

What is PFK1 allosterically inhibited and activated by?

Answer 6

Inhibited by PEP,Citrate and ATP
Activated by a high concentration of AMP

Question 7

What are covalent modifications?
What do they target?

Answer 7

Enzymes catalysed alterations of synthesised proteins
Modifications can target a single type of amino acid and will change the chemical properties of the site