Question

Phenyl-methane-sulfonyl-fluoride (PMSF) inactivates serine proteases by binding covalently to the catalytic serine residue at the active site; this enzyme-inhibitor bond is not cleaved by the enzyme. This is an example of what kind of inhibition? A) Irreversible B) Competitive C) Non-competitive D) Mixed E) pH inhibition

Answer 1

Phenyl-methane-sulfonyl-fluoride (PMSF) inactivates serine proteases by binding covalently to the catalytic serine residue at the active site, this enzyme-inhibitor bond is not cleaved by the enzyme. This is an example of an Irreversible kind of inhibition.

Explanation:

•    Cell Lysates are prepared by using Phenyl-methane-sulfonyl-fluoride (PMSF). This PMSF is an enzyme inhibitor that inactivates serine proteases.
•     It inactivate the serine proteases by attaching with the catalytic serine, Which was in an active state.
•    The PMSF bond was not separated by the enzyme. So this action cannot be repeated. Hence it is an irreversible kind of inhibition.
•     Handling of PMSF should be done in a fume hood and while handling it we should wear gloves.