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

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.