High temperatures will cause enzyme structures to dissociate (break apart).
The major thing that has an effect on an enzyme is heat. If the enzyme is exposed to a large amount of heat than it denatures, which means that it is no longer functional. Enzymes work at their best at an OPTIMUM range, that is at about 30-35 degrees Celsius. The enzyme will denature at about 47-50 degrees Celsius.
Freezing doesn't effect the enzymes since freezing does not permanently affect enzyme structure. Boiling permanently changes the structure and can change the enzymes.
Enzymes are proteins and temperature have profound effect on their activity. At 100 degree Celsius enzyme amylase denatures meaning its structure changes irreversibly. At that point it renders useless and cannot breakdown starch.
Easily Explained thusly: When the key is in the lock the Enzyme has one Structure, and when the key is not in the lock the Enzyme has another Structure. Note that the presence of a key may either activate or deactivate an Enzyme, depending upon the conditions.
The function of an enzyme is dependent on the shape of the enzyme. The structure and shape determines what the enzyme can do.
They would be stopped because the enzyme is denatured from the high temperature. High temperature usually speed them up, but after 45 degrees celsius it becomes denatured.
enzyme catalyze the biochemical reactions by lowering their activation energy. An enzyme which take part in such reaction wont be lost or gained any chemical structure and it would be the same after the reaction.
They are said to be denatured.Their tritiary structure is lost.
Denature enzyme activity
denaturation
An enzyme
To a certain point, heat will increase enzyme activity because more collisions will be taking place between the enzyme and substrates. However, if there is too much heat, an enzyme can denature (change its shape) and inactivate. This is caused because the increase in heat disrupts the bonds in the tertiary structure of the enzyme. Due to the disruption of bonds, the enzyme can no longer interact with the substrates.