Definition of enzymes:
Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. Some enzymes help break large molecules into smaller pieces that are more easily absorbed by the body. Other enzymes help bind two molecules together to produce a new molecule. The molecules that an enzyme works with are called substrates. The substrates bind to a region on the enzyme called the active site. Enzymes are protein macromolecules. They have a defined amino acid sequence and are typically 100-500 amino acids long. They have a defined three-dimensional structure. They act as a catalyst to a chemical or biochemical reaction, with a defined mechanism. Enzymes catalyze all kinds of chemical reactions that are involved in growth, blood coagulation, healing, diseases, breathing, digestion, reproduction, and many other biological activities.