Question

Q2: Describe negative feedback inhibition. Q3: Catalysts are believed to lower the activation energy of the transition state in a chemical reaction. [30% Points) Q4: Describe the difference between reversible and irreversible inhibitors. Give an example of each. [30% Points]

Answer 1

Ans 2) The accumulation of the end product of the metabolic pathway will inhibit the enzyme synthesis which is required to catalyze the earlier reaction of the pathway is known as negative feedback inhibition. The first enzyme is always allosteric.

Ans 3) Catalysts speed up the reaction by lowering the activation energy and thus, now the molecules with less kinetic energy can also attain the transition state which will result in the faster reaction in both the directions.

Ans 4) Reversible inhibitors are those inhibitors which bind to the active site of the enzyme non-covalently and the enzyme can regain its function once the inhibitor is removed.Example Ethanol (Ethanol is used in the treatment of methanol poisoning.It competitively inhibits methanol and binds to the enzyme known as alcohol dehydrogenase. This is how it inhibits methanol poisoning)Wheras,Non-reversible inhibitors bind to the enzyme covalently and inactivate them irreversibly.Example is Iodoacetate. (It is inhibitor of papain and glyceraldehyde-3- phosphate dehydrogenase and combines with sulfhydryl groups on the active site of them and makes those enzymes irreversible inactive.