... The deduced amino acid sequence of FDH from Mycobacterium vaccae N10 (McFDH) was identical to that of Pseudomonas sp. 101 (PsFDH) except for two amino acid residues: isoleucine-35 (threonine in PsFDH) and glutamate-61 (lysine in PsFDH). ... To examine the role of the two amino acid residues in the thermostability of the enzymes, glutamate-61 of McFDH was replaced by glutaminyl, prolyl and lysyl residues by site-directed mutagenesis. ...