Thermus thermophilus A4株由来・新規耐熱性β-ガラクトシダーゼおよび基質複合体のX線結晶構造解析 X-ray Crystallography of a Novel Thermostable β-Galactosidase from Thermus thermophilus A4, and Its Complex Structure with Galactose

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β-Galactosidase from Thermus thermophilus A4 (A4-β-Gal) is stable at 70°C for 20 h. It belongs to the glycosyl hydrolase family (GF) 42, and enzymes in GF-42 are stable under extreme circumstances such as high temperature or high salt concentration. In order to obtain the structural basis of its reaction mechanism and stability, we conducted X-ray crystallography of the enzyme. We identified the structure of free and galactose-bound A4-β-Gal at 1.6 A and 2.2 A resolution, respectively. The A4-β-Gal has a "flower pot-like" trimeric structure. The monomer structure of A4-β-Gal is composed of three domains. N-terminal domain (domain A) contains a galactose binding site and has a TIM barrel fold. We identified the residues interacting with the galactose. Since Trp182, a residue related to molecular symmetry, constitutes a part of the active site pocket, the trimeric conformation is necessary for A4-β-Gal to retain enzyme activity. We also identified G1u141 and G1u312 as catalytic residues for A4-β-Gal on the basis of the structural evidence. Glu 141 and G1u312 are located close to the C-termini of the fourth and seventh β-strands of the barrel structure, indicating that GF-42 belongs to 4/7 superfamily.

収録刊行物

  • 応用糖質科学 : oyo toshitsu kagaku = Journal of applied glycoscience

    応用糖質科学 : oyo toshitsu kagaku = Journal of applied glycoscience 49(2), 175-180, 2002-04-01

    The Japanese Society of Applied Glycoscience

参考文献:  17件中 1-17件 を表示

被引用文献:  2件中 1-2件 を表示

各種コード

  • NII論文ID(NAID)
    10008253644
  • NII書誌ID(NCID)
    AN10453916
  • 本文言語コード
    JPN
  • 資料種別
    REV
  • ISSN
    13403494
  • NDL 記事登録ID
    6142457
  • NDL 雑誌分類
    ZP24(科学技術--化学・化学工業--糖・澱粉)
  • NDL 請求記号
    Z17-15
  • データ提供元
    CJP書誌  CJP引用  NDL  J-STAGE 
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