Back to Search
Start Over
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
- Source :
-
Biochemical & Biophysical Research Communications . Mar2012, Vol. 419 Issue 1, p72-76. 5p. - Publication Year :
- 2012
-
Abstract
- Abstract: Thaumatin, an intensely sweet-tasting plant protein, elicits a sweet taste at 50nM. 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. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 0006291X
- Volume :
- 419
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Biochemical & Biophysical Research Communications
- Publication Type :
- Academic Journal
- Accession number :
- 73177122
- Full Text :
- https://doi.org/10.1016/j.bbrc.2012.01.129