The efficient application of biocatalysts requires the; availability of sui
table: enzymes with high activity and stability under process conditions, d
esired substrate selectivity and high enantioselectivity. However, wild-typ
e enzymes: often need to be optimized La fulfill these requirements. Two: r
ather contradictory tools can be used on a, molecular level to create tailo
r-made bio-catalysts: directed evolution and rational protein design.