As an enzyme is a protein, if the tertiary structure of an
enzyme is changed significantly it can't function, this isn't
reversible and the tertiary structure is too damage to
rebuild and this is called denaturation.
Having a higher temperature will increase the rate of which the
molecules move, resulting in the molecules gaining more kinetic
energy resulting in the molecules colliding more often and if the
kinetic energy of both enzyme molecules and substrate molecules is
increased, there will be an increased number of collisions
What are they?
Enzymes make reactions go
faster in digestive and metabolic
processes. They are called
'catalysts' because they speed up
the reaction by lowering the
amount of energy needed to get
the reaction started.
The Enzyme is the blue protein
and the substrate is the purple
molecule and when these fit
together at the active site it
makes a enzyme substrate
Enzyme induced fit hypothesis
When a substrate molecule collides with an enzyme, if its
composition is specifically correct, the shape of the enzyme's
Active Site will change so that the substrate fits into it and an
Enzyme-Substrate Complex can form. This produced a product
called a enzyme product complex. The product is a different
shape from the substrate so it can no longer fit in the active site so
it moves away. The enzyme is now able to catalyse the same
reaction with another substrate molecule
Enzymes and pH
Enzymes have different optimum pH. At optimum pH the concentration of hydrogen
ions in solution gives the tertiary structure of the enzyme the best overall shape, and
this shape holds the active site in the shape that best fits the substrate
Enzymes usually work in a fairly narrow pH range. Changes to pH, could result in a fall of reaction rate
because the shape of the enzyme molecule is disrupted so the shape of the active site is changed, even if the
change is slight.
The optimum pH for an enzyme depends on where it normally works. For example, intestinal enzymes have an
optimum pH of about 7.5. Enzymes in the stomach have an optimum pH of about 2.
Enymes and concentration
As the enzyme concentration increases,more active sites become available
More enzyme substrate complexes form
If the enzyme concentration increases further, a point will be reached where all substrate
molecules are occupying enzyme active sites.
As the substrate concentration increases, collisions increase, so more enzyme substrate complexes
form,so more products are formed.
If the concentration increases further, a point will be reached where the reaction rate reaches a