10.542 – Biochemical Engineering Spring 2005 Applications of Enzyme Catalysis – Biocatalysis • Working definition – the use of an enzyme-catalyzed reaction to convert a single starting compound to a single product o distinguished from the use of whole cells for multi-step synthetic pathways, which also use enzymes to catalyze each conversion Why use enzyme catalysis over traditional (usu. solvent-based) organic synthesis? ( Rozzell, J. D. "Commercial scale biocatalysis: myths and realities." Bioorg Med Chem 7, no. 10 (October 1999): 2253-61. ) • Catalyst selectivity/specificity • Mild reaction conditions • Environmentally friendly, “green chemistry” • High catalytic efficiency Ü Greatest interest industrially is for production of chiral compounds (see handout for examples) Substrate selectivity versus substrate range • Industrial emphasis on selectivity is most often in the context of stereoselectivity, i.e., selective conversion or production of one enantiomer, but • The best industrial enzymes will have a broad substrate range, i.e., the ability the catalyze the same type of reaction (attack the same functional group) with a variety of substrates. Example – Subtilisin (serine protease) Natural reaction: peptide bond hydrolysis, though activity against esters was known NH NH NH R 1 O R 2 O R 3 O NH OH R 1 O N H 2 NH R 2 O R 3 O Unnatural reaction: resolution of a racemic ester mixture for production of a pharmaceutical intermediate (Courtesy of Merck & Co. Used with permission.) N N F OMe O MeO O F N N F OMe O HO O F N N F OMe O MeO O F H H DHP Methyl Ester S-DHP Methyl Ester R-DHP Acid +