Biochem lecture #14 (March 12)

Question 1

What are the 4 types of irreversible inhibitors that we looked at?

Answer 1

The 4 types are Nonspecific Covalent, Transition state analogue, affinity Label, and Mechanism based.

Question 2

What does a Nonspecific covalent inhibitor bind to?

Answer 2

Any amino acid side chain, that’s why it’s nonspecific.

And so it wouldn’t mimic the substrate at all.

Question 3

What mechanism is the reverse of the alpha,beta-elimination?

Answer 3

MICHAEL Addition is the reverse of the alpha,beta-elimination reaction.

Question 4

What does an enzyme ending in “kinase” do?

Answer 4

KINASE is the name for an enzyme that transfers phosphate.

Question 5

What are the 5 general mechanisms of catalysis that follow substrate binding?

Answer 5

1. The use of Binding Energy to Drive Enzymatic Reactions:
   A special case of which is induced fit, where the substrate and/or enzyme change their structure.
2. Covalent catalysis: An active site residue covalently binds to the substrate during the catalytic cycle.
3. Acid-base catalysis: A molecule other than water is the proton donor/acceptor.
4. Catalysis by approximation: Enhancement of reaction rates by bringing multiple substrates close together in space (proximity effect).
5. Metal ion catalysis: Metal ions can be specifically coordinated in the active site to drive the reaction through conformational or chemical mechanisms (e.g. acting as reactive nucleophile)
   Cofactor: Usually metals and trace elements that confer a property to the enzyme (metalloenzyme) that it would not possess in its absence.

Question 6

Cofactor vs Coenzyme?

Answer 6

Cofactor is a nonorganic molecule that affects

Coenzyme: Complex organic molecules that participate in enzymatic reactions as transient carriers of specific functional groups, but that are not irreversibly changed (either unmodified or regenerated) during catalysis.
BCH2333-2024 Rev