An enzyme is a biological catalyst. This means it speeds up a reaction without being used up in the reaction.
Enzymes enable functions in the body to occur fast enough to be useful to humans. Enzymes are specific to one reaction only.
A can only act on fats turning them into glycerol and fatty acids.
A can only act on proteins converting them into amino acids.
Ancan only act on starch converting them into sugars.
If an amylase enzyme was put into a test tube of protein, no change would occur, likewise if you were to add lipase to a test tube of starch.
This is relatively easy to show. If you add iodine to starch it turns blue-black. When starch gets converted to sugars, the iodine is released and the solution turns orange again.
If you add lipase or protease to the test-tube, no reaction takes place and the solution stays the same blue-black colour.
If you were to add amylase, the solution turns from blue-black to gold again. The point to take from this is enzymes are specific, they can only act on one substrate, one reaction.
All enzymes are made of , so all enzymes are long chains of amino acids.
They have a specific 3D structure that is made by these chains of amino acids folding onto themselves.
The shape of an enzyme fits the substrate it acts on. The active site of the enzyme is the region that the substrate attaches to temporarily in order to be broken down.
This is part of the reason why we talk about enzymes and substrates acting as locks and keys for each other, the so-called model of enzymes. The substrate fits into the active site of the enzyme like a key into a lock.
Sometimes the enzyme’s shape is altered. When this happens, the enzyme is said to be denatured.
When an enzyme is denatured, the active site no longer fits the substrate, so no reactions can take place.