β-HELICAL TRANSMEMBRANE CHANNELS: COMMENTS ON ENERGETICS, STRUCTURE, MONOVALENT AND DIVALENT CATION SELECTIVITY AND VOLTAGE DEPENDENCE

Four new bis-macrocyclic bolaamphiphiles were prepared to explore the effects of hydrophobic substitutions on ion transport. In bilayer vesicles the new compounds were remarkably similar to more hydrophilic derivatives prepared previously. Planar bilayer conductance experiments showed the new compounds induced an unique current-time signal consisting of a rapid rise time, followed by a slower decay time. Signal shape was cation dependent and was related to a modest selectivity between cations. Cation-anion selectivity was very high, approaching an ideal cation selectivity. One compound also showed voltage dependence of the signal shape and duration. Qualitative changes in signal shape, duration, and voltage dependence were provoked by variation in the electrolyte pH and by masking the head-group electrostatic interactions with low levels of barium ions. A model for the signal shape is proposed, involving a rapid current rise due to aggregate restructuring, followed by slower decay due to development of the local Donnan potential that results from the high cation-anion selectivity.Key words: ion channel, synthesis, bilayer membrane, bilayer clamp, mechanism.

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Calcium-dependent activation of protein kinase C. The role of the C2 domain in divalent cation selectivity.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)49502-1 ◽

1993 ◽

Vol 268 (31) ◽

pp. 23580-23584

Author(s):

J.H. Luo ◽

I.B. Weinstein

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Divalent Cation ◽

C2 Domain ◽

Calcium Dependent ◽

Cation Selectivity ◽

Kinase C

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Divalent Cation Selectivity in a Cyclic Nucleotide-Gated Ion Channel

Biochemistry ◽

10.1021/bi00041a008 ◽

1995 ◽

Vol 34 (41) ◽

pp. 13328-13333 ◽

Cited By ~ 37

Author(s):

Chul-Seung Park ◽

Roderick MacKinnon

Keyword(s):

Ion Channel ◽

Divalent Cation ◽

Cyclic Nucleotide ◽

Cation Selectivity

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An Ab Initio Investigation of the Structure and Alkaline Earth Divalent Cation Selectivity of 18-Crown-6

Journal of the American Chemical Society ◽

10.1021/ja960469n ◽

1996 ◽

Vol 118 (25) ◽

pp. 6052-6059 ◽

Cited By ~ 64

Author(s):

Eric D. Glendening ◽

David Feller

Keyword(s):

Ab Initio ◽

Divalent Cation ◽

Alkaline Earth ◽

Cation Selectivity

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Generation of artificial channels by multimerization of β-strands from natural porin

Biological Chemistry ◽

10.1515/bc.2011.063 ◽

2011 ◽

Vol 392 (7) ◽

Cited By ~ 5

Author(s):

Marco Lolicato ◽

Simona Reina ◽

Angela Messina ◽

Francesca Guarino ◽

Mathias Winterhalter ◽

...

Keyword(s):

Escherichia Coli ◽

Voltage Dependence ◽

Structural Elements ◽

Planar Bilayer ◽

Bilayer Membranes ◽

Conserved Motif ◽

Basic Module ◽

Transmembrane Channels ◽

Recombinant Technology ◽

Bacterial Porins

Abstract General diffusion porins are passive transmembrane channels. We have explored the possibility to create artificial nanopores starting from natural β-barrel structures. Structural elements of bacterial porins were used to build a series of artificial nanopores. The basic module was selected by multi-alignment of general diffusion porins. The sequence corresponded to a highly conserved motif containing two β-strands, which was obtained from Escherichia coli OmpF. Dimeric to octameric repeats were obtained through cDNA recombinant technology. The hexameric repeat was used to test its properties. This protein was expressed, purified and reconstituted in the planar bilayer membranes. It was able to form channels in membranes with a conductance of 300 pS in 150 mm KCl and did not show any relevant voltage-dependence.

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