UC Davis

1,4 dicarbonyls are very important building blocks for many biologically and pharmaceutically active compounds including pharmaceuticals, pigments and pesticides. However, the synthesis of 1,4 dicarbonyls is a major bottleneck in industry. The conventional method for 1,4 dicarbonyl synthesis is the Stetter reaction, which features the addition of an aldehyde donor into an enone acceptor. One of the various drawbacks of this method is non-specific addition and creation side products such as 1,2 dicarbonyls. Enzymes are known to be highly specific and so far, two types of thiamine pyrophosphate (TPP) dependent enzymes have shown the ability to synthesize 1,4 dicarbonyl compounds and are termed stetterases: MenD and PigD (along with close homologs HapD and SeAAS). In this work, a major step is taken towards discovery of novel stetterases. A library of 77 thiamine pyrophosphate dependent enzymes is screened and assayed for stetterase activity with various donor and acceptor substrates. The substrate range of MenD is expanded and a novel stetterase is discovered. Homology modelling and catalytic site analysis is performed on known stetterases as a step towards stetterase design for specific substrates.