3VHF

plant thaumatin I at pH 8.0

Summary for 3VHF

• Entry DOI: 10.2210/pdb3vhf/pdb
• Related: 3AL7 3ALD 3AOK 3VHG
• Descriptor: Thaumatin I, GLYCEROL (3 entities in total)
• Functional Keywords: thaumatin family, mainly beta, taste protein, sweet receptor, aril, sweet-tasting protein, plant protein
• Biological source: Thaumatococcus daniellii (katemfe)
• Total number of polymer chains: 1
• Total formula weight: 22412.23

Authors

Masuda, T.,Mikami, B.,Kitabatake, N.,Tani, F. (deposition date: 2011-08-24, release date: 2012-05-16, Last modification date: 2024-11-06)

Primary citation

Masuda, T.,Ohta, K.,Mikami, B.,Kitabatake, N.,Tani, F.
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
Biochem.Biophys.Res.Commun., 419:72-76, 2012

PubMed 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.

PubMed: 22326916
DOI: 10.1016/j.bbrc.2012.01.129

Experimental method

X-RAY DIFFRACTION (1.39 Å)