Biocatalysis is an inherently green methodology providing a valuable alternative for many chemical reactions. Enzymes are proteins that function as biocatalysts and their prominent advantage for green chemistry is that they are renewable, nontoxic, and biodegradable. Enzyme-catalyzed reactions show unprecedented chemoselectivity, regioselectivity, and stereoselectivity often avoiding the need for protection/ deprotection steps. The reactions generally do not form side products, which helps to eliminate complex separation and purication procedures. Most biocatalytic processes are run at temperatures slightly above ambient and at near-neutral pH in environmentally benign, mostly aqueous systems. Because biocatalytic processes provide economic and environmental benets, these processes compete well with chemical methodologies. The best-known attributes and features of biocatalysis clearly coincide with the Twelve Principles of Green Chemistry as outlined by Anastas and Warner (Table 5.1).1