TOWARDS NOVEL BIOCATALYSTS VIA PROTEIN DESIGN - THE CASE OF LIPASES

During the past 3 years, the tertiary structures of several lipases ha ve been solved by X-ray analysis. The structures revealed unique featu res such as hydrophobic ''patches'' on the surface, presumably involve d in lipid supersubstrate binding, and a lid structure which covers th e active site in the absence of substrate. Only very recently the firs t X-ray structure of a bacterial lipase has been solved, and further s tructural features different from lipases of eukaryotic origin became apparent. Many lipase genes have been cloned and sequenced recently, a nd expression systems for the preparation of recombinant enzymes in go od yields are available. As an example, the lipase from Rhizopus oryza e has been successfully expressed by us in Escherichia coli, and the r esulting inclusion bodies were renatured in high yields. Consequently, the mechanism of action of lipases is now being studied via site-dire cted mutagenesis, and the rational design of lipases for the selective transformation of substrates is presently addressed in several labora tories.