Crystal data and thermal expansion of tricalciumborate

Majling, J.; Figusch, V.; Hanic, F.; Wiglasz, V.; Corba, J

doi:10.1016/0025-5408(74)90062-2

Cited by 16 publications

(12 citation statements)

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“…The accumulated evidence, obtained from polyphosphate kinase assay (Figure ), analytical isoelectric focusing (Figure ), and reaction to o -toluidine stain and exopolyphosphatase, indicates that a polyP chain of ∼15 units is held by ionic forces within KcsA oligomers. Given the molecular characteristics of PHB and polyP ( − ) and their demonstrated roles in ion selection and transport ( − ), one should not find their presence in an ion channel surprising. PHB, by virtue of its electron-donating oxygens closely spaced along a flexible backbone, is capable of solvating salts of hard cations; its amphiphilic nature allows it to penetrate hydrophobic regions inaccessible to water.…”

Section: Discussionmentioning

confidence: 99%

“…PHB, by virtue of its electron-donating oxygens closely spaced along a flexible backbone, is capable of solvating salts of hard cations; its amphiphilic nature allows it to penetrate hydrophobic regions inaccessible to water. PolyP, a polymorphic polyanion with a high density of negative charge, strongly attracts cations and has a well-known ability to discriminate among them by charge ( , ).…”

Section: Discussionmentioning

confidence: 99%

“…The individual and combined molecular properties of PHB and polyP make them well suited to engage in selective transfer of cations across membranes. PHB, a linear polymer of ( R )-3-hydroxybutyrate, is an amphiphilic polyester that forms ion-conducting complexes with salts ( − ); polyP, a linear polymer of phosphoryl units joined by high-energy phosphoanhydride bonds, has a high capacity for ion exchange and ability to discriminate among cations by charge ( , ). Complexes of the two polymers, isolated from bacterial plasma membranes or prepared from the synthetic polymers, form voltage-activated calcium-selective channels in planar lipid bilayers that display many of the characteristics of protein calcium channels ( − ).…”

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confidence: 99%

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Streptomyces lividans Potassium Channel Contains Poly-(R)-3-hydroxybutyrate and Inorganic Polyphosphate

Reusch

1999

Biochemistry

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The Streptomyces lividans KcsA potassium channel, a homotetramer of 17.6 kDa subunits, was found to contain two nonproteinaceous polymers, namely, poly-(R)-3-hydroxybutyrate (PHB) and inorganic polyphosphate (polyP). PHB and polyP are ubiquitous cellular constituents with a demonstrated capacity for cation selection and transport. PHB was detected in both tetramer and monomer species of KcsA by reaction to anti-PHB IgG on Western blots, and estimated as 28 monomer units of PHB per KcsA tetramer by a chemical assay in which PHB is converted to its unique degradation product, crotonic acid. PolyP was detected in KcsA tetramers, but not in monomers, by metachromatic reaction to o-toluidine blue stain on SDS-PAGE gels. A band of free polyP was also visible, suggesting that polyP is released when tetramers dissociate. The exopolyphosphatase of Saccharomyces cerevisiae degraded the free polyP, but tetramer-associated polyP was not affected, indicating it was inaccessible to the enzyme. PolyP in KcsA was estimated as 15 monomer units per tetramer by an enzymatic assay in which polyphosphate kinase is used to transfer phosphates from polyP to [(14)C]ADP, yielding [(14)C]ATP. The experimentally determined isoelectric point of KcsA tetramer was 6.5-7.5, substantially more acidic than the theoretical pI of 10.3, and consistent with the inclusion of a polyanion. The results suggest that PHB is covalently bound to KcsA subunits while polyP is held within tetramers by ionic forces. It is posited that KcsA protein creates an environment in which PHB/polyP is selective for K(+). The basic amino acids attenuate the negative charge density of polyP, thereby transforming the cation binding preference from multivalent to monovalent, and discrimination between K(+) and Na(+) is accomplished by adjusting the ligand geometry in cation binding cavities formed by PHB and polyP.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Streptomyces lividans Potassium Channel Contains Poly-(R)-3-hydroxybutyrate and Inorganic Polyphosphate

Reusch

1999

Biochemistry

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“…The density measured by heavy liquids was 3.10(2) gcm -3, the calculated density being 3.11 gcm -3. In Table 1, the properties are compared with those of synthetic Ca3BzO6 reported by Suzuki and Hira (1970), and Majling et al (1974). The value of the birefringence of takedaite was larger than that of synthetic Ca3B206.…”

Section: Physical and Optical Propertiesmentioning

confidence: 90%

“…The unit cell dimensions, refined by least squares from the X-ray powder diffraction data of takedaite, were a = 8.638(1) and c = 11.850(2)A. The X-ray powder data are given in Table 2, and compared with that of synthetic Ca3B206 reported by Sch~ifer (1968) and Majling et al(1974).…”

Section: X-ray Studiesmentioning

confidence: 99%

Takedaite, a new mineral from Fuka, Okayama Prefecture, Japan

1995

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Takedaite, Ca3B206, has been found in crystalline limestone near gehlenite-spurrite skams at Fuka, Okayama Prefecture. It occurs as aggregates of granular crystals up to 0.8 mm long and 0.3 mm wide. The mineral is associated with nifontovite, olshanskyite, pentahydroborite, frolovite, sibirskite, calcite and an unidentified mineral, is white or pale gray, and has a vitreous luster. Takedaite is trigonal with space group of R3c, a = 8. 638(1), c = 11.850(2)A, Z = 6. The strongest lines in the X-ray powder pattern [d in A (/) (hkl)] arc 2.915(100) (113), 1.895(75)(223), 2.756(61)(104), 2.493(44)(300), 2.044(21) (214,131), 2.160(19)(220), 1.976(18)(006), 1.549(12)(306). The Vickers microhardness is 478 kg mm -2 and the Mohs hardness 4.5. The density is 3.10(2) g cm -3 (meas.) and 3.11 gcm -3 (calc.). Wet chemical analyses give the values CaO 71.13%, B203 28.41%, ig. loss 0.14%, and total 99.68%. The empirical formula calculated on the basis of O = 6 is Ca3.053BL96506, with the simplified formula of Ca3B206.

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Figs. 6 - 8, Tables 6 - 9

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Landolt-Börnstein - Group III Condensed Matter

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Crystal data and thermal expansion of tricalciumborate

Cited by 16 publications

References 3 publications

Streptomyces lividans Potassium Channel Contains Poly-(R)-3-hydroxybutyrate and Inorganic Polyphosphate

Streptomyces lividans Potassium Channel Contains Poly-(R)-3-hydroxybutyrate and Inorganic Polyphosphate

Takedaite, a new mineral from Fuka, Okayama Prefecture, Japan

Figs. 6 - 8, Tables 6 - 9

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