Simply speaking, enzymes act as catalysts for metabolic processes in the body. Without them, these processes would not occur at all or at the rate necessary for sustaining life. Enzymes are specialized, as in, they do not work with all substrates, but only the specific ones they are designed for. Consequently, the active sites on substrates are shaped to fit a specific enzyme. Enzymes work by binding with the substrate at the active site, which starts catalysis, the process of changing the substrate. When this is complete, the enzyme releases, and the substrate is now the product.
An enzyme is a specialized protein produced within an organism which is capable of catalysing a specific chemical reaction. Since the enzyme acts as a catalyst it is sometimes referred to as a bio-catalysts. A catalyst influences the rate of a chemical reaction, usually without undergoing any change itself. In this respect an enzyme differs from a normal catalyst. The enzyme may participate in a reaction by combining with the substrate. Enzymes have been divided into six groups, oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Enzymes show striking specificity. They catalyse specific reactions of specific substrates.