Enzymes are proteins that stimulte reactions. There are catabolisms (= breaking down molecules) and anabolisms(= building up molecules).
Enzymes break down nutritional constituents into nutriens. They are the sbustance in our body that digest, but they do also all other reactions where our body builds up or breaks down molecules.
Working The working of enzymes is very specific: each enzyme can only break down or build up one specific substance, e.g. only for starch. This substance we call a substrate. We can compare a enzyme with a key: the key only work in one specific lock to open the door.
The working of an enzyme is dependent from the temperature: when the temperature rises or declines, it's working speed changes and their shape will change, the result is that it doesn't fit anymore on its substrate. This proces we call denaturation, because the enzyme becomes inactive. That's why our body temperature has to stay constant: the enzymes in our body works the best at this temperature.
A third point where the working of an enzyme depends on is the degree of acidity (measured in pH). The enzyme activity increases or decreases as the degree of acidity changes. Enzymes like pepsin work properly on an pH of 3, while trypsine works best at an pH of 8.
