Crystal structure of the sweet-tasting protein thaumatin II at 1.27 Å |
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Authors: | Tetsuya Masuda Keisuke Ohta Fumito Tani Bunzo Mikami Naofumi Kitabatake |
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Institution: | aDivision of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan;bDepartment Natural Resources, Graduate School of Global Environmental Studies, Kyoto University, Uji, Kyoto 611-0011, Japan;cDivision of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan |
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Abstract: | Thaumatin, an intensely sweet-tasting protein, elicits a sweet taste sensation at 50 nM. Here the X-ray crystallographic structure of one of its variants, thaumatin II, was determined at a resolution of 1.27 Å. Overall structure of thaumatin II is similar to thaumatin I, but a slight shift of the Cα atom of G96 in thaumatin II was observed. Furthermore, the side chain of residue 67 in thaumatin II is highly disordered. Since residue 67 is one of two residues critical to the sweetness of thaumatin, the present results suggested that the critical positive charges at positions 67 and 82 are disordered and the flexibility and fluctuation of these side chains would be suitable for interaction of thaumatin molecules with sweet receptors. |
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Keywords: | Thaumatin Sweet-tasting protein Amino-acid variations Positive charge |
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