Browsing by Author "Shi, GS"

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    Solubility enhancement of aromatic amino acids and peptides in aqueous solution of divalent transition-metal cations - QENS study
    (International Conference on Neutron Scattering, 2017-07-12) Yu, DH; Shi, GS; Mole, RA; Fang, HP
    Generally, the solubility of aromatic amino acids decreases in solution containing multivalent transition-metal ions, such as Cu2+, Pt2+, Pd2+and Co3+, due to the formation of complex precipitates. Surprisingly, we have observed considerably enhanced solubility of tryptophan (Trp) in CuCl2 aqueous solution with a high local concentration of Cu2+ at the surface of Trp [Phys. Rev. Lett. 117, 238102 (2016)]. The solubility increases by 2-5 times that of Trp in pure water. Based on first principle calculations, this unexpected phenomenon is attributed to the strong interaction between Cu2+and the aromatic ring in Trp, referred to as cation–? interaction which modifies the electron distribution of the aromatic ring in Trp and increases the water–aromatic ring interaction.
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    Unexpectedly enhanced solubility of aromatic amino acids and peptides in an aqueous solution of divalent transition-metal cations
    (American Physical Society, 2016-12-02) Shi, GS; Dang, Y; Pan, TT; Liu, X; Liu, H; Li, S; Zhang, LJ; Zhao, HW; Li, SP; Han, JG; Tai, RZ; Zhu, Y; Li, J; Ji, Q; Mole, RA; Yu, DH; Fang, HP
    We experimentally observed considerable solubility of tryptophan (Trp) in a CuCl2 aqueous solution, which could reach 2-5 times the solubility of Trp in pure water. Theoretical studies show that the strong cation-π interaction between Cu2+ and the aromatic ring in Trp modifies the electronic distribution of the aromatic ring to enhance significantly the water affinity of Trp. Similar solubility enhancement has also been observed for other divalent transition-metal cations (e.g., Zn2+ and Ni2+), another aromatic amino acid (phenylalanine), and three aromatic peptides (Trp-Phe, Phe-Phe, and Trp-Ala-Phe). © 2016 American Physical Society.