Artificial ion channels formed by a synthetic cyclic peptide

Wang, D.; Guo, Lili; Zhang, J.; Roeske, Roger W.; Jones, Larry R.; Chen, Z.; Pritchard, C. I.

doi:10.1046/j.1397-002x.2000.00823.x

Cited by 39 publications

(28 citation statements)

References 26 publications

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“…1). Their rare characteristics compared to the other synthetic ion channels/pores, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] i.e. the possibility to install functional groups along the ion-conducting pathway, encouraged the shift of our interest from biomimicry to practical applications.…”

Section: Introductionmentioning

confidence: 99%

Synthetic multifunctional pores: deletion and inversion of anion/cation selectivity using pM and pH

et al. 2003

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We report the characterization of multifunctional rigid-rod β-barrel ion channels with either internal aspartates or arginine-histidine dyads by planar bilayer conductance experiments. Barrels with internal aspartates form cation selective, large, unstable and ohmic barrel-stave (rather than toroidal) pores; addition of magnesium cations nearly deletes cation selectivity and increases single-channel stability. Barrels with internal arginine-histidine dyads form cation selective (P K ϩ/P Cl Ϫ = 2.1), small and ohmic ion channels with superb stability (single-channel lifetime > 20 seconds). Addition of "protons" results in inversion of anion/cation selectivity (P Cl Ϫ/P K ϩ = 3.8); addition of an anionic guest (HPTS) results in the blockage of anion selective but not cation selective channels. These results suggest that specific, internal counterion immobilization, here magnesium (but not sodium or potassium) cations by internal aspartates and inorganic phosphates by internal arginines (but not histidines), provides access to synthetic multifunctional pores with attractive properties.

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Section: Introductionmentioning

confidence: 99%

Synthetic multifunctional pores: deletion and inversion of anion/cation selectivity using pM and pH

et al. 2003

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“…For an organic chemist entering the field without BLMs, [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] LUVs provide a user friendly and, according to the comparative studies discussed below, valid alternative. Among several possible methods to determine anion/cation selectivity of synthetic ion channels in vesicles, the HPTS assay worked best in our hands (Fig.…”

Section: Determination Of Anion/cation Selectivity In Vesicles For Symentioning

confidence: 99%

The determination of the ion selectivity of synthetic ion channels and pores in vesicles

Sakai

Matile

2006

J of Physical Organic Chem

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Organic chemists entering the field of synthetic ion channels and pores are often restricted to the characterization of their creation by fluorescence kinetics in vesicles and do not have access to conductance experiments in planar bilayer membranes. This limitation excludes the application of methods to evaluate key characteristics such as ion selectivity or voltage gating that are routine in the membrane biophysics community.

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“…2C) (2). Whereas various other rigid-rod ␤-barrel SMPs are available to cope with particular sensing requirements, SMPs other than rigid-rod ␤-barrels remain underexplored (3)(4)(5)(6)(7)(8)(9), particularly when compared with the remarkable progress made with bioengineered multifunctional pores as stochastic sensors of single analytes (10)(11)(12)(13).…”

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Enzyme screening with synthetic multifunctional pores: Focus on biopolymers

Sordé

Das

Matile

2003

Proc. Natl. Acad. Sci. U.S.A.

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This report demonstrates that a single set of identical synthetic multifunctional pores can detect the activity of many different enzymes. Enzymes catalyzing either synthesis or degradation of DNA (exonuclease III or polymerase I), RNA (RNase A), polysaccharides (heparinase I, hyaluronidase, and galactosyltransferase), and proteins (papain, ficin, elastase, subtilisin, and pronase) are selected to exemplify this key characteristic of synthetic multifunctional pore sensors. Because anionic, cationic, and neutral substrates can gain access to the interior of complementarily functionalized pores, such pores can be the basis for very userfriendly screening of a broad range of enzymes. There are compelling reasons to believe that the ''universal enzyme sensor,'' a user-friendly, noninvasive device that can detect all existing enzyme activities, belongs to the world of fiction and, despite functional proteomics, will never become reality (1, 2, ‡). However, it would be erroneous to conclude that efforts to maximize adaptability of noninvasive enzyme sensors to as many enzymes as possible are a simple waste of time. In this study, selected examples from biopolymer enzymology are used to demonstrate that a set of identical synthetic multifunctional pores (SMPs) can be used for noninvasive detection of the activity of many different enzymes (Fig. 1).In brief, if substrates bind and block the pore better than products, enzyme activity gradually removes the blocking agent and the pore can open. On the other hand, if products bind and block the pores better than the substrates, enzyme activity gradually produces blocking agents that can block the pores (Fig. 2). Thus, if there is substantial molecular recognition of either substrate or product by the same pore, the only prerequisite for detecting enzyme activities with SMP sensors is a simple method to distinguish between blocked and unblocked pores.As SMPs we introduced rigid-rod ␤-barrels 1 and 2 ( Fig. 2C) (2). Whereas various other rigid-rod ␤-barrel SMPs are available to cope with particular sensing requirements, SMPs other than rigid-rod ␤-barrels remain underexplored (3-9), particularly when compared with the remarkable progress made with bioengineered multifunctional pores as stochastic sensors of single analytes (10-13).The syntheses of barrel-stave supramolecules 1 (14) and 2 (15) from commercial biphenyl and amino acid derivatives in 19 steps overall each have been described. The characteristics of pores formed by rigid-rod ␤-barrels 1 and 2 in spherical and planar lipid bilayer membranes have also been reported (2, 14-16). Even without optimization, the extraordinary permeabilizing activity of these p-octiphenyl ␤-barrels makes it possible to perform Ͼ300,000 enzyme assays per mg of polypeptide (1).L-histidine (H) and L-arginine (R) residues at the inner barrel surface account for the multifunctionality of pore 1. Lining the ion-conducting pathway of SMP 1, these cationic residues recognize anionic substrates and products Ͼ10,000 times better than biological po...

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Artificial ion channels formed by a synthetic cyclic peptide

Cited by 39 publications

References 26 publications

Synthetic multifunctional pores: deletion and inversion of anion/cation selectivity using pM and pH

Synthetic multifunctional pores: deletion and inversion of anion/cation selectivity using pM and pH

The determination of the ion selectivity of synthetic ion channels and pores in vesicles

Enzyme screening with synthetic multifunctional pores: Focus on biopolymers

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