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Title: 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.
Authors: Masuda, Tetsuya  kyouindb  KAKEN_id  orcid (unconfirmed)
Ohta, Keisuke
Mikami, Bunzo  kyouindb  KAKEN_id
Kitabatake, Naofumi
Tani, Fumito  kyouindb  KAKEN_id
Author's alias: 桝田, 哲哉
Keywords: Thaumatin
Sweet-tasting protein
Alkaline conditions
Issue Date: 2-Mar-2012
Publisher: Elsevier Inc.
Journal title: Biochemical and biophysical research communications
Volume: 419
Issue: 1
Start page: 72
End page: 76
Abstract: 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.
Rights: © 2012 Elsevier Inc.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
DOI(Published Version): 10.1016/j.bbrc.2012.01.129
PubMed ID: 22326916
Appears in Collections:Journal Articles

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