title: Involvement of alanine 103 residue in kinetic and physicochemical properties of glucose isomerases from Streptomyces species.
abstract: The Ala103 to Gly mutation, introduced within the glucose isomerase from Streptomyces sp. SK (SKGI) decreased its catalytic efficiency (k(cat)/K(m)) toward D-glucose from 7.1 to 3 mM(-1) min(-1). The reverse counterpart replacement Gly103Ala introduced into the glucose isomerase of Streptomyces olivochromogenes (SOGI) considerably improved its catalytic efficiency to be 6.7 instead of 3.2 mM(-1) min(-1). This later mutation also increased the half-life time of the enzyme from 70 to 95 min at 80 degrees C and mainly modified its pH profile. These results provide evidence that the residue Ala103 plays an essential role in the kinetic and physicochemical properties of glucose isomerases from Streptomyces species.
authors.affiliation: Laboratory of Prokaryotic Enzymes and Metabolites, Center of Biotechnology of Sfax, Sfax, Tunisia.
authors.forename: Mohamed Ali
authors.initials: MA
authors.lastname: Borgi
authors.forename: Moez
authors.initials: M
authors.lastname: Rhimi
authors.forename: Samir
authors.initials: S
authors.lastname: Bejar
mesh_terms: D000409:Alanine / Q000235:genetics*; D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism; D005998:Glycine / Q000235:genetics; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D005947:Glucose; D000409:Alanine; D005998:Glycine