title: Crystal structure of the sweet-tasting protein thaumatin II at 1.27Å.
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.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan. t2masuda@kais.kyoto-u.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Masuda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohta
authors.forename: Fumito
authors.initials: F
authors.lastname: Tani
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kitabatake
mesh_terms: D018360:Crystallography, X-Ray; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation
chemical_list: D010940:Plant Proteins; C057542:thaumatin II protein, Thaumatococcus daniellii