title: Langmuir monolayers of a cholesterol-armed cyclen complex that can control enantioselectivity of amino acid recognition by surface pressure.
abstract: The cholesterol-armed cyclen Na(+) complex formed stable Langmuir monolayers at the air-water interface. The π-A isotherm displayed a reasonable limiting molecular area of ∼1.57 nm(2) and the areas expanded when amino acids were dissolved in water, indicating the efficient accommodation in the monolayers. Brewster angle microscopy (BAM) images exhibited almost no defects of the compressed Langmuir monolayers regardless of the presence of amino acids. Based on the idea that the increase in the limiting molecular areas corresponds to the amount of the adsorbed amino acid, the binding constants of three enantiomeric amino acids, namely valine (Val), leucine (Leu), and phenylalanine (Phe), were calculated at different surface pressures. Remarkably, a surface pressure dependent enantioselectivity of amino acid recognition was observed. Upon compression of the monolayers, the binding constants of amino acids increased accompanying an inversion of chiral selectivity from the D- to L-form in the case of Val and, conversely, from L- to D-form in the case of Phe.
authors.affiliation: World Premier International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan. michinobu.t.aa@m.titech.ac.jp
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Michinobu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shinoda
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Hill
authors.forename: Kazuko
authors.initials: K
authors.lastname: Fujii
authors.forename: Tomoko N
authors.initials: TN
authors.lastname: Player
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsukube
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ariga
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry*; D000080027:Cyclams; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008853:Microscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D011312:Pressure; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013379:Substrate Specificity; D013499:Surface Properties
chemical_list: D000596:Amino Acids; D000080027:Cyclams; D006571:Heterocyclic Compounds; C038072:cyclen; D002784:Cholesterol