Before we start you should already know what enzymes actually are, so watch our video: "What are enzymes"
Each enzyme has conditions under which it functions best.
In other words, the point at which the rate of reaction is at its highest.
Amongst these conditions, the most well-known are temperature and pH.
If these conditions vary from the optimal level for the enzyme, the enzyme can become denatured,
and consequently the rate of reaction will decrease.
However different enzymes have different optimal conditions. One consequence of denaturation can be
a disturbance of the organisms inner balance, also called homeostasis.
For example, the activity of protease [enzyme] which is not optimal can affect
Protein Digestion in the body. If we look in more detail,
denaturation of enzymes, and any other protein, means that the shape of the enzyme has changed in some way.
Usually a permanent change.
The activity of an enzyme
depends heavily on its shape, particularly of the active site which binds at the substrate or substrates.
This change of structure means that the active site is not shaped for optimal rate of reaction.
So for example if the temperature of the environment is too high for the specific enzyme, it may become
denatured.
Typically enzymes that operate in
warm-blooded animals tend to have an optimal temperature of 37 degrees Celsius (which is body temperature).
Then, as the temperature rises
above that, the rate of reaction rapidly falls because the active site has changed shape.
Whereas enzymes in bacteria that live in the thermal vents have a much higher optimal temperature.
Now here comes the chemistry behind this. When temperatures increase, the
individual amino acids that make up the enzyme vibrate at a higher frequency.
This results in the breaking of the hydrogen bonds between amino acids and different
parts of the protein chain, leading to a change of shape.
At even higher temperatures, bonds between individual amino acids, called peptide acids, can break
leading the protein to fragment. Another important variable is pH.
A pH level which is either too high or too low for a particular enzyme can lead to change of protein structure.
Different enzymes will have different optimal pHs.
The optimal pH for an enzyme depends upon where it normally works.
Pepsin works in the acidic stomach and so
unsurprisingly has an optimum pH of 2. How does pH affect the active site of enzymes if
the pH is too low for the enzyme? The concentration of hydrogen ions will be greater than normal and
these will interact with amino acids, leading to a change in shape of the active site,
thus reducing the rate of reaction. So from this video
you should know that enzymes have optimal conditions under which they operate.
Different enzymes have different preferred conditions, with some
preferring acidic conditions and others preferring alkali conditions.
Temperature is also an important factor, with most enzymes having an optimal temperature of 37 degrees
and then denaturing above that.