title: Thermotoga neapolitana homotetrameric xylose isomerase is expressed as a catalytically active and thermostable dimer in Escherichia coli.
abstract: The xylA gene from Thermotoga neapolitana 5068 was expressed in Escherichia coli. Gel filtration chromatography showed that the recombinant enzyme was both a homodimer and a homotetramer, with the dimer being the more abundant form. The purified native enzyme, however, has been shown to be exclusively tetrameric. The two enzyme forms had comparable stabilities when they were thermoinactivated at 95 degrees C. Differential scanning calorimetry revealed thermal transitions at 99 and 109.5 degrees C for both forms, with an additional shoulder at 91 degrees C for the tetramer. These results suggest that the association of the subunits into the tetrameric form may have little impact on the stability and biocatalytic properties of the enzyme.
authors.affiliation: Department of Chemical Engineering, North Carolina State University, Raleigh 27695-7905, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Hess
authors.forename: V
authors.initials: V
authors.lastname: Tchernajenko
authors.forename: C
authors.initials: C
authors.lastname: Vieille
authors.forename: J G
authors.initials: JG
authors.lastname: Zeikus
authors.forename: R M
authors.initials: RM
authors.lastname: Kelly
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002384:Catalysis; D019281:Dimerization; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D006089:Gram-Negative Anaerobic Bacteria / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase