What are the main characteristics of an enzyme?

Main characterstics of enzymes are-

1. It is a protein and is, therefore, destroyed by heating.
2. It acts only on one kind of substance called the substrate i.e. it is specific.
3. It always forms the same end-product(s) from the substrate.
4. It only affects the rate of a chemical reaction and always speeds up the reaction.
5. Like a catalyst, it can be used again and again.
6. It acts best only at a particular pH,i.e. at a particular degree of acidity or alkalinity.
7. It acts best within a narrow temperature range, usually between 35°and 40°C which is also called the optimum temperature.