Q.Who proposed 'Lock and Key hypothesis' and 'Induced fit hypothesis'?

Enzyme action proceeds through the formation of a temporary enzyme-substrate (ES) complex: the substrate binds to a specific pocket on the enzyme called the active site, the reaction is carried out while the substrate is held in this complex, and the product is then released, freeing the enzyme to bind another substrate molecule. Schematically, E + S -> ES -> E + P.

Forming this complex is precisely what allows the enzyme to speed up the reaction: by stabilising an intermediate transition state, the enzyme lowers the amount of activation energy the reaction needs, so that the same conversion that would otherwise require climbing over a high energy barrier can now proceed with a much smaller energy input. …