Atomic structure of the sweet-tasting protein thaumatin I at pH 8.0 reveals the large disulfide-rich region in domain II to be sensitive to a pH change.

• 桝田, 哲哉

• Ohta, Keisuke

• Mikami, Bunzo

• Kitabatake, Naofumi

• Tani, Fumito

抄録

Thaumatin, an intensely sweet-tasting plant protein, elicits a sweet taste at 50 nM. Although the sweetness remains when thaumatin is heated at 80 °C for 4h under acid conditions, it rapidly declines when heating at a pH above 6.5. To clarify the structural difference at high pH, the atomic structure of a recombinant thaumatin I at pH 8.0 was determined at a resolution of 1.0Å. Comparison to the crystal structure of thaumatin at pH 7.3 and 7.0 revealed the root-mean square deviation value of a Cα atom to be substantially greater in the large disulfide-rich region of domain II, especially residues 154-164, suggesting that a loop region in domain II to be affected by solvent conditions. Furthermore, B-factors of Lys137, Lys163, and Lys187 were significantly affected by pH change, suggesting that a striking increase in the mobility of these lysine residues, which could facilitate a reaction with a free sulfhydryl residue produced via the β-elimination of disulfide bonds by heating at a pH above 7.0. The increase in mobility of lysine residues as well as a loop region in domain II might play an important role in the heat-induced aggregation of thaumatin above pH 7.0.

収録刊行物

• Biochemical and biophysical research communications

  Biochemical and biophysical research communications 419 (1), 72-76, 2012-03-02

  Elsevier Inc.

キーワード

• Thaumatin
• Sweet-tasting protein
• Alkaline conditions
• Heat
• SHELXL
• Hydrogen-atoms
• Hydrogen-Ion Concentration
• Models, Chemical
• Plant Proteins/chemistry
• Protein Structure, Tertiary
• Sweetening Agents/chemistry
• Taste

詳細情報

• CRID: 1050001335769914496
• NII論文ID: 120005293583
• NII書誌ID: AA00564395
• ISSN: 0006291X
• HANDLE: 2433/175270
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles