Mycolic Acid Cyclopropane Synthase Enzymes as New Biocatalysts for Green Cyclopropanation Reactions

"Cyclopropane rings are a key structural motif that may be found in a wide range of natural products, chemicals, fragrances and pharmaceuticals. Current methods for the manufacturing of cyclopropane-containing molecules show significant limitations in terms of safety, environmental impact and green metrics. Only a few biocatalytic methodologies for the asymmetric synthesis of cyclopropanes have been developed so far, and they rely on repurposed or artificial heme enzymes (P450, myoglobin). However, these approaches suffer from significant limitations in terms of ""green chemistry"" and industrial application since they require stoichiometric amounts of hazardous diazo-compound reagents as co-substrates. Overcoming these limitations is a critical challenge that underscores the need for further research and development in 'green chemistry' and industrial application of biocatalysis. Mycolic Acid Cyclopropane Synthases (MACSs) are pivotal cyclopropane synthase enzymes found in mycobacteria, such as M. tuberculosis. They are a group of homologous enzymes in the mycolic acid biosynthesis pathway, and they are crucial in catalysing the cyclopropanation of double bonds. Since MACSs use S-adenosyl-L-methionine (SAM) as a methylene donor rather than diazo-carbene co-substrates, they present a viable option for creating mild and sustainable cyclopropanation biocatalysts. Furthermore, with their ability to catalytic cyclopropanate short- to long-chain unsaturated fatty acids and their ease of bioengineering, these enzymes present a novel and exciting opportunity for future biocatalyst development. This project focuses on the characterization and development of MACSs as cyclopropanating biocatalysts through enzyme engineering approaches."