Biocatalysis refers to the use of isolated enzymes or whole cells as catalysts for the synthesis of organic molecules. Enzymes are protein catalysts that accelerate chemical transformations inside a living organism. As essential components of all living systems, they catalyze the chemical transformations in cellular metabolism and are responsible for the creation of a large number and many types of molecules required for life. Biocatalysis, by exploiting nature's catalysts, offers exciting opportunities to capture nature's enormous catalytic power and synthetic diversity in chemical synthesis.