Midterm Topics: Enzymes

Question 1

How do enzymes work? How do they change energetics of a chem reaction?

Answer 1

• They work by changing their tertiary and quaternary structure. This impacts the activity can be either increased (stimulated, activated) or decreased (inhibited)
• Change energetics because they are catalysts. They decrease activation energy which increases reaction rate

Question 2

What determines enzyme-substrate interactions?

Answer 2

Their shape and their chemistry

Question 3

What makes enzymes specific for a particular substrate?

Answer 3

The shape; enzymes shape must be particular/complementary to the shape of the substrate

Question 4

What is an allosteric inhibition and activation?

Answer 4

• Inhibition: enzyme can’t work as well when the inhibitor is bound because it changes the active sites shape and won’t let substrate connect. It lowers the affinity
• Activation: increases/facilitates the reaction rate. increases affinity

Question 5

What is covalent modification/modulation?

Answer 5

• Phosphorylation: adding phosphate group to a protein
• some enzymes are activated or deactivated by another enzyme (kinase) that covalently attaches a phosphate to them
• Phosphorylations can turn enzyme activity off
• Phosphate can be added to a side chain with a free hydroxyl (-OH) group