Converting a fatty acid binding protein to an artificial transaminase: novel catalysts by chemical and genetic modification of a protein cavity

Despite the widespread use of enzymes in synthetic applications, their “native” characteristics are often insufficient for many chemical transformations. To meet this challenge we have used protein cavities for the design of new biocatalysts. A pyridoxamine derivative (PX) was chemically tethered within the spacious cavity of intestinal fatty acid binding protein (IFABP). The cysteine residue, which anchors the cofactor of the artificial transaminase IFABP-PX, can be placed in different regions by site-directed mutagenesis. Catalytic reactions with high enantioselectivities (up to 94% ee) and varying substrate specificity of the transamination of α-keto and amino acids were achieved. IFABP-PX mutants were further optimized by introducing lysine residues in order to mimic the active site of native transaminases.