Chapter 5 - Enzymatic Decarboxylation as a Tool for the Enzymatic Defunctionalization of Hydrophobic Bio-based Organic Acids

Abstract

The decarboxylation of organic acids is an emerging tool for the synthesis of bio-based olefins. Although terminal alkenes are the key intermediates for the chemical industry, they play only a marginal role in nature. Nature relies on the activation of carboxylic acids via thioesters or phosphate esters. Formation of terminal alkenes coupled to their selective functionalization has been rarely observed in metabolism. Enzymatic systems for the conversion of organic acids to alkenes are therefore scarce. Interestingly, several systems were identified in the last few years that catalyze the direct decarboxylation of organic acids to terminal olefins (D’Espaux etal.,2015; Herman and Zhang, 2016; Kang and Nielsen,2017; Lennen and Pfleger,2013; Schwartz etal.,2014; Zhou etal.,2014). This decarboxylation often proceeds under mild reaction conditions and produces terminal olefins without formation of unwanted internal alkenes. Nature offers different, highly promising catalytic systems with substrate spectra ranging from mid- to long-chain olefins. Most decarboxylases involved in lipid modification have been discovered in the last 10 years, and the recent elucidation of structure and mechanisms has laid the basis for an optimization by molecular engineering, leading to variants with improved catalytic activity and extended substrate spectrum.