(1) Department of Bioscience and Biotechnology, Sejong University, Seoul, 143-747, South Korea
Abstract:
Among single-site mutations of l-arabinose isomerase derived from Geobacillus thermodenitrificans, two mutants were produced having the lowest and highest activities of d-tagatose production. Site-directed mutagenesis at these sites showed that the aromatic ring at amino acid 164 and the size
of amino acid 475 were important for d-tagatose production. Among double-site mutations, one mutant converted d-galactose into d-tagatose with a yield of 58% whereas the wild type gave 46% d-tagatose conversion after 300 min at 65 °C.
Received 31 August 2005; Revisions requested 27 September 2005; Revisions received 8 November 2005; Accepted 8 November 2005