W. E. Armstrong and Social Anthropology at Cambridge 1922-1926

Urry, James

doi:10.2307/2802439

Cited by 13 publications

(13 citation statements)

References 32 publications

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“…Synthetic and naturally occurring ion channels are amphiphilic structures with an outer coat of nonpolar residues and a lining of polar and charged residues (1)(2)(3)(4)(5)(6)(7). In this report, we demonstrate the formation of synthetic nonproteinaceous ion channels from two structurally distinct polymers that share the above attributes in a cooperative fashion.…”

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confidence: 99%

Proof for a nonproteinaceous calcium-selective channel in Escherichia coli by total synthesis from ( R )-3-hydroxybutanoic acid and inorganic polyphosphate

Das

Lengweiler

Seebàch

et al. 1997

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

118

111

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Traditionally, the structure and properties of natural products have been determined by total synthesis and comparison with authentic samples. We have now applied this procedure to the first nonproteinaceous ion channel, isolated from bacterial plasma membranes, and consisting of a complex of poly(3-hydroxybutyrate) and calcium polyphosphate. To this end, we have now synthesized the 128-mer of hydroxybutanoic acid and prepared a complex with inorganic calcium polyphosphate (average 65-mer), which was incorporated into a planar lipid bilayer of synthetic phospholipids. We herewith present data that demonstrate unambiguously that the completely synthetic complex forms channels that are indistinguishable in their voltage-dependent conductance, in their selectivity for divalent cations, and in their blocking behavior (by La 3؉ ) from channels isolated from Escherichia coli. The implications of our finding for prebiotic chemistry, biochemistry, and biology are discussed.Synthetic and naturally occurring ion channels are amphiphilic structures with an outer coat of nonpolar residues and a lining of polar and charged residues (1-7). In this report, we demonstrate the formation of synthetic nonproteinaceous ion channels from two structurally distinct polymers that share the above attributes in a cooperative fashion. The polymers in question, poly(3-hydroxybutyrate) (PHB) and inorganic polyphosphate (polyP), are ubiquitous constituents of biological cells (8)(9)(10)(11)(12). PHB is an amphiphilic homopolymer of (R)-3-hydroxybutanoic acid, which in bacteria is synthesized from acetyl-CoA in three steps: dimerization to form acetoacetyl-CoA, reduction by NADPH to form 3-hydroxybutyrylCoA, and polymerization to form PHB (13,14). Under growth-limiting conditions, some bacteria produce highmolecular-mass PHB (60,000 to Ͼ1,000,000 Da) in amounts of up to 90% of the cell dry weight. PolyP, a polyanion composed of phosphate residues linked by anhydride bonds, is formed by repetitive phosphoryl transfer from ATP or other high-energy phosphates (15-17).Both PHB and polyP have molecular characteristics that are consistent with a role in ion conduction. PHB has salt-solvating properties that derive from the recurrence of electrondonating ester carbonyl oxygens at regular and frequent intervals along its flexible backbone (18,19). The solvating abilities of PHB are illustrated by studies that demonstrate its capacity to transport cations across methylene chloride layers in U-tubes (20), form ion-conducting complexes with lithium perchlorate (21), or large-conductance nonselective ion channels in planar lipid bilayers (22). PolyP has a flexible backbone and high density of monovalent negative charges that create a large capacity for ion exchange and a stronger affinity for multivalent over monovalent cations (23).Plasma membrane vesicles of Escherichia coli contain complexes of PHB and polyP that function as calcium-selective channels in planar lipid bilayers (24). In vivo, such channels may control the influx of calcium to ma...

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confidence: 99%

Proof for a nonproteinaceous calcium-selective channel in Escherichia coli by total synthesis from ( R )-3-hydroxybutanoic acid and inorganic polyphosphate

Das

Lengweiler

Seebàch

et al. 1997

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

118

111

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“…He entered Cambridge University before the First World War, but at the outbreak of the war, he joined the Royal Army Medical Corps. He was wounded in action and lost a leg in 1915 (Urry :413). He returned to Cambridge and in 1918, he completed his degree in the Moral Sciences Tripos with psychology as special subject.…”

Section: We Armstrong and The Cambridge School Of Anthropologymentioning

confidence: 99%

“…, Rivers ). This had a special appeal to him as a ‘confirmed logician’ given to a priori deductive reasoning and model‐building (Langham :213; Urry :420). There was also a ‘late Rivers’ who regarded forms of social organization as results of historical diffusion.…”

Section: We Armstrong and The Cambridge School Of Anthropologymentioning

confidence: 99%

Dogomomo Xmas, Kwangwe's Races, and a Murder: W.E. Armstrong and the Rossel Island Money

Liep

2015

Oceania

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“…[1] Their permeability is highly selective because of the occurrence of specific carriers or channel-formers for ions or organic molecules. [2] Several physiologically important channel proteins have been isolated and sequenced, [3] and the preparation of artificial ion channels is an ongoing ambitious goal attracting considerable efforts. [4] To this aim, different strategies have been used.…”

Section: Introductionmentioning

confidence: 99%

Zinc(II) as an Allosteric Regulator of Liposomal Membrane Permeability Induced by Synthetic Template-Assembled Tripodal Polypeptides

et al. 2002

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RNA‐Lego: Die Verwendung von natürlichen RNA‐Schalter‐Aptameren in synthetischen RNA‐Schaltern (siehe Bild) dürfte die Bandbreite künstlicher RNA‐Regulatoren enorm vergrößern. Es wird gezeigt, dass Thiaminpyrophosphat‐Aptamere in gentechnisch veränderten Funktionseinheiten als hochempfindliche Schalter der Genexpression in nichtmodifizierten Organismen eingesetzt werden können. Der Ansatz illustriert, dass intrinsische Metabolite als externe Effektoren zellulärer Funktionen nutzbar sind.

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W. E. Armstrong and Social Anthropology at Cambridge 1922-1926

Cited by 13 publications

References 32 publications

Proof for a nonproteinaceous calcium-selective channel in Escherichia coli by total synthesis from ( R )-3-hydroxybutanoic acid and inorganic polyphosphate

Proof for a nonproteinaceous calcium-selective channel in Escherichia coli by total synthesis from ( R )-3-hydroxybutanoic acid and inorganic polyphosphate

Dogomomo Xmas, Kwangwe's Races, and a Murder: W.E. Armstrong and the Rossel Island Money

Zinc(II) as an Allosteric Regulator of Liposomal Membrane Permeability Induced by Synthetic Template-Assembled Tripodal Polypeptides

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