title: A hexokinase with broad sugar specificity from a thermophilic bacterium.
abstract: A recombinant thermophilic Thermus caldophilus GK24 hexokinase, one of the ROK-type (repressor protein, open reading frames, and sugar kinase) proteins, exists uniquely as a 120 kDa molecule with four subunits (31 kDa), in contrast to eukaryotic and bacterial sugar kinases which are monomers or dimers. The optimal temperature and pH for the enzyme reaction are 70-80 degrees C and 7.5, respectively. This enzyme shows broad specificity toward glucose, mannose, glucosamine, allose, 2-deoxyglucose, and fructose. To understand the sugar specificity at a structural level, the enzyme-ATP/Mg2+-sugar binding complex models have been constructed. It has been shown that the sugar specificity is probably dependent on the interaction energy occurred by the positional proximity of sugars bound in the active site of the enzyme, which exhibits a tolerance to modification at C2 or C3 of glucose.
authors.affiliation: Genome Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333, Republic of Korea.
authors.forename: Jungdon
authors.initials: J
authors.lastname: Bae
authors.forename: Dooil
authors.initials: D
authors.lastname: Kim
authors.forename: Yongseok
authors.initials: Y
authors.lastname: Choi
authors.forename: Sukhoon
authors.initials: S
authors.lastname: Koh
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Joong
authors.initials: J
authors.lastname: Su Kim
authors.forename: Seong Hoon
authors.initials: SH
authors.lastname: Moon
authors.forename: Bo-Hyun
authors.initials: BH
authors.lastname: Park
authors.forename: Miri
authors.initials: M
authors.lastname: Park
authors.forename: Hye-Eun
authors.initials: HE
authors.lastname: Song
authors.forename: Suk-In
authors.initials: SI
authors.lastname: Hong
authors.forename: Dae-Sil
authors.initials: DS
authors.lastname: Lee
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006593:Hexokinase / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity; D013824:Thermus / Q000201:enzymology*
chemical_list: D011994:Recombinant Proteins; D005632:Fructose; D000255:Adenosine Triphosphate; D006593:Hexokinase; D008274:Magnesium; D005947:Glucose; D008358:Mannose