title: Purification and characterization of 3-isopropylmalate dehydrogenase from a thermoacidophilic archaebacterium Sulfolobus sp. strain 7.
abstract: 3-Isopropylmalate dehydrogenase was purified (about 2000-fold) to homogeneity for the first time from an archaebacterium, Sulfolobus sp. strain 7. The enzyme showed an apparent molecular mass of about 110 kDa by gel filtration and a single 36-kDa polypeptide band on SDS-PAGE, suggesting tri- or tetrameric structure. The pI value was 6.9. The N-terminal amino acid sequence was similar to enzymes from other sources. The enzyme activity was greatly stimulated by the presence of Mn2+, Cd2+, Mg2+, or Co2+. In contrast to 3-isopropylmalate dehydrogenase from other sources, monovalent cations such as K+ and Na+ were neither essential for activity nor stability of the protein. The enzyme was extraordinarily thermostable.
authors.affiliation: Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Yoda
authors.forename: Y
authors.initials: Y
authors.lastname: Anraku
authors.forename: H
authors.initials: H
authors.lastname: Kirino
authors.forename: T
authors.initials: T
authors.lastname: Wakagi
authors.forename: T
authors.initials: T
authors.lastname: Oshima
mesh_terms: D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D002413:Cations, Divalent; D004795:Enzyme Stability; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017421:Sequence Analysis; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D002413:Cations, Divalent; D000429:Alcohol Oxidoreductases; D050539:3-Isopropylmalate Dehydrogenase