title: Unexpectedly Enhanced Solubility of Aromatic Amino Acids and Peptides in an Aqueous Solution of Divalent Transition-Metal Cations.
abstract: We experimentally observed considerable solubility of tryptophan (Trp) in a CuCl_{2} 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 Cu^{2+} 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., Zn^{2+} and Ni^{2+}), another aromatic amino acid (phenylalanine), and three aromatic peptides (Trp-Phe, Phe-Phe, and Trp-Ala-Phe).
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Guosheng
authors.initials: G
authors.lastname: Shi
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Yaru
authors.initials: Y
authors.lastname: Dang
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Pan
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Liu
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.|Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Shaoxian
authors.initials: S
authors.lastname: Li
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhao
authors.affiliation: School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Shaoping
authors.initials: S
authors.lastname: Li
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Jiaguang
authors.initials: J
authors.lastname: Han
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
authors.forename: Renzhong
authors.initials: R
authors.lastname: Tai
authors.affiliation: Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, No. 516, Jungong Road, 200093, Shanghai, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Physics and Astronomy, the University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: Jichen
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Biophysics, Hebei University of Technology, Tianjin 300401, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Ji
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors.forename: R A
authors.initials: RA
authors.lastname: Mole
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors.forename: Dehong
authors.initials: D
authors.lastname: Yu
authors.affiliation: Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Fang
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D002413:Cations, Divalent; D004151:Dipeptides; D008670:Metals; D010455:Peptides / Q000737:chemistry*; D010649:Phenylalanine; D012995:Solubility; D028561:Transition Elements; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000596:Amino Acids; D002412:Cations; D002413:Cations, Divalent; D004151:Dipeptides; D008670:Metals; D010455:Peptides; D028561:Transition Elements; C026650:phenylalanylphenylalanine; C014309:alanylphenylalanine; D010649:Phenylalanine; D014364:Tryptophan