Enzymes are highly selective catalysts which can greatly accelerate both the rate and specificity of metabolic reactions, which range from the digestion of food to the synthesis of DNA. Almost all the chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life. Due to their wide range of activities based on their nature of reaction, Enzymes are classified according to their enzyme catalyzing reaction. The Enzyme Commission number (EC Number) is a numerical classification scheme for enzymes based on the chemical reactions they catalyze.
Enzymes are large biomolecules required for the numerous chemical interconversions that sustain life. These are generally known as "Biocatalyst". Enzymes are highly efficient, which can increase reaction rates by 100 million to 10 billion times faster than any normal chemical reaction.