Living organisms are continuously producing many macromolecules for their daily metabolic needs. In some cases, these organisms perform polymer syntheses that may be impractical to accomplish with conventional chemistry. Microorganisms have not become a common component of commercial synthetic processes due to the many unresolved problems with their handling and control. The challenges facing the use of microorganisms on the commercial level include the difficulty of identifying a microbe that demonstrates a specific synthetic capability, the microorganism's susceptibility to chemical toxins, strain stability, and slow reaction kinetics.

The use of isolated enzymes provides the same advantages of microbes without the many troubles. Consisting of, and breaking down into amino acids, enzymes can be considered a sustainable reagent. The products of enzymatic synthesis and polymerization are frequently biodegradable. There are currently many types of enzymes being used in polymerization processes. Many of the commonly used enzymes belong to the lipase family; however,horseradish peroxidase and cellulase have also been used as catalysts for chemical synthesis.

Lipases play a major role in the turnover of lipids. These enzymes are found in animals, plants, fungi and bacteria. Triglycerides cannot cross the intestinal barrier. Therefore many hydrolytic steps are necessary to obtain all the energy in the hydrocarbon chain of lipids. These enzymes have made their way into industry by being enantioselective catalysts in aqueous, organic and other media. They have been found to catalyze polymerization reactions from ring opening to transesterification.

Candida antarctica Lipase B	Horseradish peroxidase