Detection of the activity of ion channels and pores by circular dichroism spectroscopy: G-quartets as functional CD probes within chirogenic vesicles.


:We introduce a method to detect the activity of ion channels and pores with circular dichroism (CD) spectroscopy. G-quartets obtained by potassium templated self-assembly of 5'-guanosine monophosphate (GMP) are used as CD probes, the bee-toxin melittin as representative pore and gramicidin A as representative ion channel. To detect the activity of pores with CD spectroscopy, vesicles were loaded with GMP at concentrations above the dissociation constant (K(D)) of G-quartets. GMP efflux through added pores was detectable as CD silencing due to G-quartet disassembly by local dilution. The Hill plot of melittin with Hill coefficient n = 4 was faithfully reproduced with CD detection. The same was true for counterion-activated cell-penetrating peptides, confirming their ability to mediate the export of anions such as GMP. The same method is not applicable to the CD detection of the activity of ion channels because GMP efflux does not occur. To do that, the potassium selectivity of G-quartets was used. Namely, vesicles were loaded with GMP at concentrations above the dissociation constant (K(D)) of G-quartets stabilized by potassium. External M/K cation exchange resulted in CD silencing by M/K antiport through the added ion channel followed by G-quartet disassembly within the vesicle. Reversal of the direction of M/K antiport was achieved with Cs-loaded vesicles and detected as the appearance of the CD signature of G-quartets in response to K influx. Corroborative examples with gramicidin A include CD detection of the Eisenman I selectivity sequence and the Hill coefficient.






Hennig A,Matile S




Has Abstract


2008-09-01 00:00:00












  • Stereospecific pH-dependent degradation kinetics of R- and S-naproxen-beta-l-O-acyl-glucuronide.

    abstract::The hydrolysis and acyl migration of biosynthetic S-naproxen-beta-l-O-acyl glucuronide (I) and R-naproxen-beta-l-O-acyl glucuronide (II) was followed by HPLC. Nine first-order kinetic rate constants for the hydrolysis and acyl migration between the beta-l-O-acyl glucuronide, its alpha/beta-2, alpha/beta-3-, alpha/beta...


    pub_type: 杂志文章


    authors: Mortensen RW,Sidelmann UG,Tjørnelund J,Hansen SH

    更新日期:2002-05-05 00:00:00

  • Chiral counter-current chromatography: A survey of its instrument, mechanism, procedure, and applications.

    abstract::The chiral separation by counter-current chromatography has made great progress in the past three decades. It has become increasingly popular in the field of chiral separation, and many applications have been introduced during the last years. This review mainly focuses on the current topics, applications, and trends i...


    pub_type: 杂志文章,评审


    authors: Duan WD,Huang XY,Di DL

    更新日期:2020-10-01 00:00:00

  • Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid-liquid extraction.

    abstract::Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activitie...


    pub_type: 杂志文章


    authors: Cui X,Ding Q,Shan RN,He CH,Wu KJ

    更新日期:2019-06-01 00:00:00

  • Synthesis and circular dichroism studies of N,N-bis(2-quinolylmethyl)amino acid Cu(II) complexes: determination of absolute configuration and enantiomeric excess by the exciton coupling method.

    abstract::We report a method to determine the absolute configuration of alpha-amino acids by exciton coupled circular dichroism (ECCD). Naturally occurring amino acids were successfully derivatized with 2-bromomethylquinoline. Complexation of these conformationally flexible ligands with Cu(II) salts yielded defined propeller-li...


    pub_type: 杂志文章


    authors: Holmes AE,Zahn S,Canary JW

    更新日期:2002-06-01 00:00:00

  • Unprecedented crystallization and X-ray crystal structure of racemic N(alpha)-(t-butyloxycarbonyl)-L-L-phenylalanine N-methoxy-N-methylamide.

    abstract::Weinreb amide 3 was synthesized using isobutyl chloroformate, carbonyldiimidazole, or ethylcarbodiimide as the coupling agent in the reaction of Boc-phenylalanine with O,N-dimethylhydroxylamine hydrochloride. An optically active oil was isolated along with an optically inactive solid irrespective of the type of coupli...


    pub_type: 杂志文章


    authors: Zheng X,Donkor IO,Miller DD,Ross CR 2nd

    更新日期:2000-01-01 00:00:00

  • Chiroptical properties of cation complexes of chiral phenazino-18-crown-6 ether-type hosts.

    abstract::Herein we report CD spectroscopic studies on complexes of (R,R)-dimethyl-, (R,R)-diisobutyl-, and (S,S)-di-sec-butyl-phenazino-18-crown-6 ligands (Scheme 1) with selected alkali (Na+, K+), alkaline earth (Mg2+, Ca2+), and transition-metal (Ag+, Zn2+, Ni2+, Cd2+, Pb2+) cations. The complexation was monitored in the 300...


    pub_type: 杂志文章


    authors: Szarvas S,Szalay L,Vass E,Hollósi M,Samu E,Huszthy P

    更新日期:2005-06-01 00:00:00

  • A stereodynamic fluorescent probe for amino acids. Circular dichroism and circularly polarized luminescence analysis.

    abstract::The use of stereodynamic probes is becoming one of the leading strategies for the fast and effective determination of enantiomeric excess. Recently, we reported a series of novel molecular architectures based on a modified tris(2-pyridylmethyl)amine complex (TPMA), which are able to amplify the electronic CD, in the c...


    pub_type: 杂志文章


    authors: Carmo Dos Santos NA,Badetti E,Licini G,Abbate S,Longhi G,Zonta C

    更新日期:2018-01-01 00:00:00

  • Determination of enantiomeric excess of ethyl 3,5-dihydroxy-6-benzyloxy hexanoate by chiral reverse phase high performance liquid chromatography.

    abstract::A simple and reliable chiral HPLC method was developed for the determination of enantiomeric excess of a chiral dihydroxy intermediate for the chemoenzymatic synthesis of side chain of statin drugs. After evaluating different columns and conditions, the four stereoisomers of ethyl 3,5-dihydroxy-6-benzyloxy hexanoate w...


    pub_type: 杂志文章


    authors: Liu JH,Yu BY,Chen YJ

    更新日期:2008-01-01 00:00:00

  • A Simple ¹³C NMR Method for the Discrimination of Complex Mixtures of Stereoisomers: All Eight Stereoisomers of α-Tocopherol Resolved.

    abstract::A simple one-dimensional (13)C NMR method is presented to discriminate between stereoisomers of organic compounds with more than one chiral center. By means of this method it is possible to discriminate between all eight stereoisomers of α-tocopherol. To achieve this the chiral solvating agent (S)-(+)-1-(9-anthryl)-2,...


    pub_type: 杂志文章


    authors: Lankhorst PP,Netscher T,Duchateau AL

    更新日期:2015-11-01 00:00:00

  • Chiroptical studies on supramolecular chirality of molecular aggregates.

    abstract::The attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low-molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoro...


    pub_type: 杂志文章,评审


    authors: Sato H,Yajima T,Yamagishi A

    更新日期:2015-10-01 00:00:00

  • Enantiospecific analysis of 8-prenylnaringenin in biological fluids by liquid-chromatography-electrospray ionization mass spectrometry: application to preclinical pharmacokinetic investigations.

    abstract::8-Prenylnaringenin (8PN) is a naturally occurring bioactive chiral prenylflavonoid found most commonly in the female flowers of hops (Humulus lupulus L.). A stereospecific method of analysis for 8PN in biological fluids is necessary to study the pharmacokinetic disposition of each enantiomer. A novel and simple liquid...


    pub_type: 杂志文章


    authors: Martinez SE,Lakowski TM,Davies NM

    更新日期:2014-08-01 00:00:00

  • Copper(II) complexes of N2-alkyl-(S)-amino acid amides as chiral selectors for dynamically coated chiral stationary phases in RP-HPLC.

    abstract::Copper(II) complexes of N2-octyl-(S)-phenylalaninamide (Noc-Phe-NH2), N2-dodecyl-(S)-phenylalaninamide (Ndo-Phe-NH2), and N2-octyl-(S)-norleucinamide (Noc-NLeu-NH2), dynamically adsorbed on a reversed-phase C18 column, were able to perform the direct enantiomeric separation of unmodified amino acids, amino acid amides...


    pub_type: 杂志文章


    authors: Galaverna G,Corradini R,Dossena A,Marchelli R,Dallavalle F

    更新日期:1996-01-01 00:00:00

  • Tautomerism of 4-hydroxy-2,5-dimethyl-3(2H)-furanone: evidence for its enantioselective biosynthesis.

    abstract::Chiral natural flavor compounds exhibit characteristic enantiomeric excesses due to stereoselective, enzymatically catalyzed reactions during biogenesis. Although the enzymatic formation of the strawberry key flavor compound 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF; Furaneol(R)) is anticipated, the naturally occurr...


    pub_type: 杂志文章


    authors: Raab T,Hauck T,Knecht A,Schmitt U,Holzgrabe U,Schwab W

    更新日期:2003-08-01 00:00:00

  • Solid-state circular dichroism and hydrogen bonding, part 2: the case of hypothemycin re-investigated.

    abstract::The impact of crystalline forces on the solid-state circular dichroism (CD) spectrum of hypothemycin (), a biologically active molecule extracted from natural sources, has been analyzed by means of time-dependent density functional theory CD calculations. Input structures were extracted from the X-ray geometry of and ...


    pub_type: 杂志文章


    authors: Pescitelli G

    更新日期:2012-09-01 00:00:00

  • Three-Dimensional Chemical Structure Search Using the Conformational Code for Organic Molecules (CCOM) Program.

    abstract::Searching the 3D structural fragments of organic molecules is challenging because of structural differences between X-ray and theoretically calculated geometries and the conformational flexibility of substituents. The codification program called Conformational Code for Organic Molecules (CCOM) can be used to unambiguo...


    pub_type: 杂志文章


    authors: Izumi H,Nafie LA,Dukor RK

    更新日期:2016-05-01 00:00:00

  • Enantioselective catalytic reduction of ketoimines with trichlorosilane promoted by readily available chiral Lewis bases.

    abstract::The straightforward synthesis of a series of enantiomerically pure Lewis basic amides by simple condensation of commercially available enantiopure diamines with picolinic acid is reported. These compounds were shown to promote the enantioselective reduction of ketoimines with trichlorosilane. Working with the model su...


    pub_type: 杂志文章


    authors: Guizzetti S,Benaglia M,Cozzi F,Rossi S,Celentano G

    更新日期:2009-01-01 00:00:00

  • Enantiomeric recognition of amino acids using a chiral spiropyran derivative.

    abstract::An optically active spiropyran 1 with a binaphthol moiety as a chiral source was synthesized. The colored merocyanine form of (R)-1 obtained by the UV irradiation remained in the presence of D-amino acids longer than with L-amino acids. ...


    pub_type: 杂志文章


    authors: Tsubaki K,Mukoyoshi K,Morikawa H,Kinoshita T,Fuji K

    更新日期:2002-10-01 00:00:00

  • From cosmic chirality to protein structure: Lord Kelvin's legacy.

    abstract::A selection of my work on chirality is sketched in two distinct parts of this lecture. Symmetry and Chirality explains how the discrete symmetries of parity P, time reversal T, and charge conjugation C may be used to characterize the properties of chiral systems. The concepts of true chirality (time-invariant enantiom...


    pub_type: 杂志文章,评审


    authors: Barron LD

    更新日期:2012-11-01 00:00:00

  • Stereochemical study of tolperisone, a muscle relaxant agent, by circular dichroism and ultraviolet spectroscopy.

    abstract::The stereochemistry of tolperisone, a chiral aryl-alkyl basic ketone was investigated by means of circular dichroism (CD) and ultraviolet (UV) spectroscopy. The unusually high optical activity of tolperisone hydrochloride in the n-->pi* region is interpreted by the presence of a chiral conformer in solution. For stere...


    pub_type: 杂志文章


    authors: Zsila F,Hollósi M,Gergely A

    更新日期:2000-11-01 00:00:00

  • Headspace gas chromatography-mass spectrometry analysis of isoflurane enantiomers in blood samples after anesthesia with the racemic mixture.

    abstract::Several in vivo and in vitro studies on the stereoselective potency of isoflurane enantiomers suggest beneficial effects of the (+)-(S)-enantiomer. In order to detect possible differences in the pharmacokinetics of isoflurane enantiomers, a clinical study of 41 patients undergoing general anesthesia maintained with ra...


    pub_type: 临床试验,杂志文章


    authors: Schmidt R,Wahl HG,Häberle H,Dieterich HJ,Schurig V

    更新日期:1999-01-01 00:00:00

  • First molecules, biological chirality, origin(s) of life.

    abstract::Origin(s) of biological chirality appear(s) to be intimately connected to origin(s) of life. Prebiotic evolution toward these important turning points can be traced back to single chiral molecules. These can be small (monomeric) units as amino acids or monosaccharides or oligomers as oligo-RNA type molecules. Earlier ...


    pub_type: 评论,杂志文章


    authors: Caglioti L,Micskei K,Pályi G

    更新日期:2011-01-01 00:00:00

  • CHIRBASE, a graphical molecular database on the separation of enantiomers by liquid-, supercritical fluid-, and gas chromatography.

    abstract::In order to cope with the increasing number of publications on the separation of enantiomers by chromatography on a chiral stationary phase, the graphical molecular database CHIRBASE was created. In the present state, the database package covers information (structural, bibliographic, and chromatographic data) on liqu...


    pub_type: 杂志文章


    authors: Koppenhoefer B,Nothdurft A,Pierrot-Sanders J,Piras P,Popescu C,Roussel C,Stiebler M,Trettin U

    更新日期:1993-01-01 00:00:00

  • Enantioselective separation of (±)-β-hydroxy-1,2,3-triazoles by supercritical fluid chromatography and high-performance liquid chromatography.

    abstract::This paper reports the enantioseparation of β-hydroxy-1,2,3-triazole derivatives, which present a broad range of biological properties, by supercritical fluid chromatography (SFC) and high-performance liquid chromatography techniques (HPLC). Polysaccharide-based chiral columns (cellulose and amylose) were used to eval...


    pub_type: 杂志文章


    authors: Alvarenga N,Porto ALM,Barreiro JC

    更新日期:2018-07-01 00:00:00

  • Stereoselective kinetics of warfarin binding to human serum albumin: effect of an allosteric interaction.

    abstract::Kinetic and equilibrium binding studies were performed on the interaction of warfarin enantiomers with human serum albumin (HSA) in the absence and presence of lorazepam acetate (LoAc) enantiomers. Binding kinetics were followed by recording changes in the fluorescence of warfarin upon binding to HSA using the stopped...


    pub_type: 杂志文章


    authors: Fitos I,Visy J,Kardos J

    更新日期:2002-05-15 00:00:00

  • Asymmetric allylation of α-ketoester-derived N-benzoylhydrazones promoted by chiral sulfoxides/N-oxides Lewis bases: highly enantioselective synthesis of quaternary α-substituted α-allyl-α-amino acids.

    abstract::Chiral sulfoxides/N-oxides (R)-1 and (R,R)-2 are effective chiral promoters in the enantioselective allylation of α-keto ester N-benzoylhydrazone derivatives 3a-g to generate the corresponding N-benzoylhydrazine derivatives 4a-g, with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a-b were...


    pub_type: 杂志文章


    authors: Reyes-Rangel G,Bandala Y,García-Flores F,Juaristi E

    更新日期:2013-09-01 00:00:00

  • Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism.

    abstract::Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2 . I...


    pub_type: 杂志文章


    authors: Zhao L,Xie J,Guo F,Liu K

    更新日期:2018-05-01 00:00:00

  • A new definition of life.

    abstract::Chirality is often glossed over in theoretical or experimental discussions concerning the origin of life, but the ubiquity of homochiral building blocks in known biological systems demands explanation. Information theory can provide a quantitative framework for understanding the role of chirality in biology. Here I sh...


    pub_type: 杂志文章


    authors: Carroll JD

    更新日期:2009-03-01 00:00:00

  • Derivatization, complexation, and absolute configurational assignment of chiral primary amines: application of exciton-coupled circular dichroism.

    abstract::We report here a sensitive method for the determination of the absolute configurations of primary amines using exciton-coupled circular dichroism (ECCD). The method works on a microgram scale by derivatization of chiral amines with quinoline chromophores. Complexation of the chiral ligands with metal ion fixes the geo...


    pub_type: 杂志文章


    authors: Zhang J,Holmes AE,Sharma A,Brooks NR,Rarig RS,Zubieta J,Canary JW

    更新日期:2003-02-01 00:00:00

  • Chiral separation and CD characterisation of enantiomeric cyclotriphosphazene derivatives.

    abstract::The gem-disubstituted cyclotriphosphazene 1 reacted with piperazine (pip) to give the piperazine-bridged derivative 2, which is expected to exist in meso and racemic forms because the two PCl (pip) groups are stereogenic. The proton-decoupled (31)P NMR spectrum of 2 gave rise to two similar sets of ABX signals in a 1:...


    pub_type: 杂志文章


    authors: Bui TT,Coles SJ,Davies DB,Drake AF,Eaton RJ,Hursthouse MB,Kiliç A,Shaw RA,Yeşilot S

    更新日期:2005-10-01 00:00:00

  • Highly diastereoselective addition of silyldihalomethyllithiums to chiral alkyl esters.

    abstract::Treatment of benzoate, formate, or trifluoroacetate esters with silyldibromomethyllithiums provides alkyl silyl mixed acetals via the 1,3-rearrangement of a silyl group from carbon to oxygen. A high level of asymmetric induction onto the acetal carbon is observed when chiral alkyl esters are employed. The stereochemic...


    pub_type: 杂志文章


    authors: Shinokubo H,Kondo J,Inoue A,Oshima K

    更新日期:2003-01-01 00:00:00