7: C–X Bond Formation

This chapter covers enzyme classes that are capable of catalysing reactions to form carbon–heteroatom bonds, including transaminases, ammonia lyases, hydratases, halohydrin dehalogenases and methyltransferases. The chapter is divided into separate sections, each detailing the formation of a specific carbon–heteroatom bond, including carbon–nitrogen, carbon–oxygen, carbon–halogen and carbon–sulfur bonds. Each section begins with a review of chemical methods of making each bond type, followed by a description of the enzyme classes capable of catalysing each bond formation. The substrate scope of each enzyme class, including its chemo-, regio- and stereoselectivity, is discussed and a general mechanism for the enzyme-catalysed reaction is presented. Where appropriate, strategies for co-factor recycling are also included. This should give the reader a rounded understanding of when and how to carry out C–X bond forming reactions using enzymes.