Mechanisms of Enzyme
Action
Lock and Key Theory
Actie site of an enzyme has a specific, 3D shape from its tertiary structure, which is
specific to its complementary substrate molecule
Only the complementary substrate molecule can fit to form an enzyme-substrate
complex (ESC)
Like how only the right key will fit in the lock it is made for
Enzymes with specific R groups then hold the substrate in place and put strain on it to
make the reaction proceed
Induced Fit Theory
Modification of the lock and key theory
Studies proved that the enzyme was not a passive recipient of the substrate
Active site is not fixed or rigid and instead moulds to the shape of the substrate for a
better fit
This further adds strain to the substrate to speed up the reaction
The enzyme returns to its original shape after
Strain on Substrate
Strain on the substrate is what actually causes the reaction
Amino acids with specific R groups come closer to the substrate and apply strain to it to
cause the reaction
The moulding in the induced fit model adds further strain to the substrate, increasing
the rate of reaction
Action
Lock and Key Theory
Actie site of an enzyme has a specific, 3D shape from its tertiary structure, which is
specific to its complementary substrate molecule
Only the complementary substrate molecule can fit to form an enzyme-substrate
complex (ESC)
Like how only the right key will fit in the lock it is made for
Enzymes with specific R groups then hold the substrate in place and put strain on it to
make the reaction proceed
Induced Fit Theory
Modification of the lock and key theory
Studies proved that the enzyme was not a passive recipient of the substrate
Active site is not fixed or rigid and instead moulds to the shape of the substrate for a
better fit
This further adds strain to the substrate to speed up the reaction
The enzyme returns to its original shape after
Strain on Substrate
Strain on the substrate is what actually causes the reaction
Amino acids with specific R groups come closer to the substrate and apply strain to it to
cause the reaction
The moulding in the induced fit model adds further strain to the substrate, increasing
the rate of reaction
