title: Ketohexokinase (ATP:D-fructose 1-phosphotransferase) from a halophilic archaebacterium, Haloarcula vallismortis: purification and properties.
abstract: Ketohexokinase (ATP:D-fructose 1-phosphotransferase [EC 2.7.1.3]), detected for the first time in a prokaryote, i.e., the extreme halophile Haloarcula vallismortis, was isolated and characterized from the same archaebacterium. This enzyme was characterized with respect to its molecular mass, amino acid composition, salt dependency, immunological cross-reactivity, and kinetic properties. Gel filtration and sucrose density gradient centrifugation revealed a native molecular mass of 100 kDa for halobacterial ketohexokinase, which is larger than its mammalian counterpart. The enzyme could be labeled by UV irradiation in the presence of [ gamma-32P]ATP, suggesting the involvement of a phosphoenzyme intermediate. Other catalytic features of the enzyme were similar to those of its mammalian counterparts. No antigenic cross-reactivity could be detected between the H. vallismortis ketohexokinase and the ketohexokinases from different rat tissues.
authors.affiliation: Radiation Biology and Biochemistry Division, Bhabha Atomic Research Centre, Bombay, India.
authors.forename: V
authors.initials: V
authors.lastname: Rangaswamy
authors.forename: W
authors.initials: W
authors.lastname: Altekar
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002845:Chromatography; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017124:Conserved Sequence; D017886:Durapatite; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005631:Fructokinases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D006216:Halobacteriaceae / Q000201:enzymology* / Q000254:growth & development; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009994:Osmolar Concentration; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D017886:Durapatite; D005631:Fructokinases; C021475:ketohexokinase