Jennifer A Littlechild
University of Exeter, UK
Title: Thermophilic enzymes with applications for industrial biocatalysis
Biography
Biography: Jennifer A Littlechild
Abstract
There is an increasing demand for new enzymes with enhanced performance and/or novel functionalities that provide
savings in time, money and energy for industrial processes in the areas of high value chemical production and other
white biotechnology applications. Only a small proportion of nature’s catalysts have been utilised for industrial biotechnology.
Th e number of enzymes explored to date remains within the range of 1-2% of known biodiversity. A problem with using
enzymes for industrial biocatalysis reactions is oft en their stability under the harsh conditions employed. Th e use of naturally
thermostable enzymes isolated from hot environments are more stable to high temperatures, extremes of pH and exposure
to organic solvents. Th e projects HOTZYME and THERMOGENE have identifi ed hydrolase and transferase enzymes of
industrial interest isolated from high temperature environments around the world. Th ese have been isolated from thermophilic
bacterial and archaeal genomes and metagenomes. A selection of these novel thermostable enzymes including cellulases,
carboxylesterases, lactonases, epoxide hydrolases, transketolases, hydroxymethyl transferases and transaminases have been
characterized both biochemically and structurally. Transaminase enzymes have received special attention for the production
of chiral amines which are important building blocks for the pharmaceutical industries. Th ese enzymes catalyse the reversible
transfer of an amino group from a donor substrate onto a ketone/aldehyde or sugar acceptor molecule. Th ey can be subdivided
into 6 classes. Th e less studied class 4 (branched chain) (R) selective, class 5 (S) selective and class 6 (sugar) enzymes have
been identifi ed. An example of the archaeal class 4 enzyme from Archaeoglobus fulgidus; a thermostable class 5 archaeal
transaminase from Sulfolobus solfataricus and class 6 sugar transaminase from A. fulgidus. Two new enzymes with interesting
substrate specifi city and stereo-selectivity have been discovered which have already been demonstrated at industrial scale for
the production of new chiral chemical building blocks.