Great tricks by old ponies :
Lipases & esterases for organic chemistry processes
Martin Schürmann and Iwona Kaluzna of InnoSyn share some recent developments in the production of lipases and esterases applied in large-scale processes
Lipases and esterases are the workhorses in industrial biocatalysis applied to the production of chemicals . Despite this , they are frequently regarded as old-fashioned in the academic world and do not achieve as much interest in literature and at conferences as some decades ago . This lack of academic recognition does not reflect their true relevance . Industrial scientists value the high intrinsic reaction rates , the often high operational stability and the unmatched chemo- , regio- and enantioselectivity of hydrolytic enzymes like nitrilases , proteases lipases and esterases . For decades the worldwide industrial production of multihundreds of thousands of tonnes / year of acrylamide from acrylonitrile has been almost exclusively performed biocatalytically with nitrile hydratases . They outcompete the best copper catalyst in terms of chemoselectivity , stopping very cleanly at the amide stage and not hydrolysing it further to the acid . 1 Lipases are used in chemical sectors ranging from bulk or base chemicals to high-value pharmaceutical intermediates because of their high productivity and operational stability ( often even in water-free reaction systems ) and their typically excellent regio- and enantioselectivity . 2 Similarly , esterases are very selective in ester hydrolyses under mild and benign conditions . However , they usually lack the productivity in organic solvents and the hydrophilic / hydrophobic interfacial activation that most lipases exhibit . 3 The application range for ester hydrolyses and syntheses in the chemical industry is vast : from lowcost biodiesel production to speciality ester synthesis as fine chemicals and kinetic resolution of racemic chiral APIs and their precursors . For the latter compound class , lipases and esterases have been studied and applied extensively in academia and industry to produce chiral esters , acids or alcohols .
PLE isoforms
Esterases originally isolated from pig liver ( PLEs ) in particular proved to be very versatile in the asymmetric kinetic resolutions and desymmetrisation of pro-chiral compounds . 4 However , the production of non-chiral non-pharma products can also profit from the excellent regio- and chemo-selectivity of lipases and esterases like PLE for example for highly selective mono-hydrolysis of achiral diesters ( Figure 1 ). 5
The biggest limitation on the full exploitation of the synthetic potential of PLEs has been their isolation from animal-derived material . This disqualified them for pharma , kosher and halal application , but also led to issues with security of supply and fluctuating quality . These issues were solved when the genes for the seven PLE isoforms were cloned and two PLE isoforms were produced in Escherichia coli strains in the Bornscheuer and Schwab / Pichler labs , as well as InnoSyn ’ s and DSM labs . 6 The isoform APLE ( PLE-1 ) was then applied as a biocatalyst in the industrial production of an E- ( 2S ) -alkyl-5-halopent-4-ene-carboxylic ester as the precursor to the renin inhibitor aliskiren . Since then , these PLE isoforms have been used for the synthesis of various pharma intermediates and other fine and speciality chemicals from gram to kg scale . These syntheses have ranged from the diester desymmetrisation of a 600 g / mol pharma intermediate to the > 99 % selective mono-hydrolysis of dimethyl adipate .
Figure 1 - Selected ester hydrolyses catalysed by PLEs in form of the animal-derived isoform mixture or as recombinantly produced single isoforms PLE-1 or PLE-7
28 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981