Probing the essential catalytic residues and substrate affinity in the thermoactive Bacillus stearothermophilus US100 L-arabinose isomerase by site-directed mutagenesis.

ABSTRACT: The L-arabinose isomerase (L-AI) from Bacillus stearothermophilus US100 is characterized by its high thermoactivity and catalytic efficiency. Furthermore, as opposed to the majority of l-arabinose isomerases, this enzyme requires metallic ions for its thermostability rather than for its activity. These features make US100 L-AI attractive as a template for industrial use. Based on previously solved crystal structures and sequence alignments, we identified amino acids that are putatively important for the US100 L-AI isomerization reaction. Among these, E306, E331, H348, and H447, which correspond to the suggested essential catalytic amino acids of the L-fucose isomerase and the L-arabinose isomerase from Escherichia coli, are presumed to be the active-site residues of US100 L-AI. Site-direct

SUBMITTER: Rhimi M 

PROVIDER: S-EPMC1855884 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature