Solvation of polymers as model for solvent effect investigation: proposition of a novel polarity scale

Malavolta, Luciana; Oliveira, Eliandre de; Cilli, Eduardo Maffud; Nakaie, Clóvis R.

doi:10.1016/s0040-4020(02)00417-9

Cited by 71 publications

(60 citation statements)

References 65 publications

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“…The synthesis was performed as described in [16]. Analytical high performance liquid chromatography (HPLC) (Waters), LC/MS (electrospray-Micromass)-mass spectrometry (theoretical m=z ¼ 1902:28; found: 1902) and amino acid analysis (Biochrom 20 Plus, from Amersham Biosciences) were used to check the homogeneity of purified Trp3.…”

Section: Peptide Synthesis and Sample Preparationmentioning

confidence: 99%

Ion channel-like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers

Salay

2004

FEBS Letters

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The cationic peptide tritrpticin (VRRFPWWWP-FLRR, Trp3) has a broad action spectrum, acting against Gram-positive and Gram-negative bacteria, as well as some fungi, while also displaying hemolytic activity. We have studied the behavior of Trp3 in planar lipid bilayers (or black lipid membrane -BLM) and were able to demonstrate its ion channel-like activity. Channel-like activity was observed in negatively charged azolectin BLM as a sudden appearance of discrete current fluctuations upon application of a constant voltage across the membrane. Trp3 formed large conductance channels (500-2000 pS) both at positive and negative potentials. In azolectin bilayers, the predominant ionchannel activity was characterized by very regular and discrete current steps (corresponding to openings) of uniform amplitude, which exhibited relatively long residence times (of the order of seconds). Occasionally, multiple conductance steps were observed, indicating the simultaneous presence of more than one open pore. In bilayers of zwitterionic diphytanoylphosphatidyl choline (DPhPC) Trp3 also showed ion-channel activity, but in a much less frequent and less prominent way. Studies of ion selectivity indicated that Trp3 forms a cation-selective channel. These results should contribute to the understanding of the molecular interactions and mechanism of action of Trp3 in lipid bilayers and biological membranes.

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Section: Peptide Synthesis and Sample Preparationmentioning

confidence: 99%

Ion channel-like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers

Salay

2004

FEBS Letters

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“…This assertion has been verified in solvent effect studies involving solvation of dozens of polymers and peptide-polymers with different polarity characteristics in nearly 30 single and mixed solvent systems [3,4].…”

Section: Resultsmentioning

confidence: 70%

“…It is of note that the dimensionless (AN+DN) scale, which ranges from zero (toluene) to almost 130 (trifluoromethanesulfonic acid) [4], has other unique advantage in terms of elucidating the solute solvation effect of solvents. The experiments detailed in a number of studies depict several examples of self-neutralizing effects occurring, for instance, when strong electrophilic trifluoroethanol, hexafluoroisopropanol or water are mixed with strong nucleophilic solvents such as dimethylsulfoxide [3,4,13,14].…”

Section: Resultsmentioning

confidence: 99%

“…The experiments detailed in a number of studies depict several examples of self-neutralizing effects occurring, for instance, when strong electrophilic trifluoroethanol, hexafluoroisopropanol or water are mixed with strong nucleophilic solvents such as dimethylsulfoxide [3,4,13,14]. In such cases, one component trends to interact with its amphoteric counterpart and does not solvate the aggregated solute molecules, inducing their dissociation.…”

Section: Resultsmentioning

confidence: 99%

“…In a conceptual departure from most prior efforts to define an accurate polarity term, we previously proposed an alternative polarity scale based on experiments designed to assess solvation of model resins and peptide-resin (microscopic measurement of bead swelling) in solvent systems broadly encompassing the polarity scale [3,4]. In these works, we have hypothesized that the 1:1 sum of Gutman's [5] electron acceptor number (AN) and electron donor number (DN) numbers would be a dimensionless, accurate polarity term.…”

Section: Introductionmentioning

confidence: 99%

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Application of Electron Paramagnetic Resonance Spectroscopy for Validation of the Novel (AN+DN) Solvent Polarity Scale

Malavolta

Poletti

Silva

et al. 2008

IJMS

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Abstract:Based on solvation studies of polymers, the sum (1:1) of the electron acceptor (AN) and electron donor (DN) values of solvents has been proposed as an alternative polarity scale. To test this, the electron paramagnetic resonance isotropic hyperfine splitting constant, a parameter known to be dependent on the polarity/proticity of the medium, was correlated with the (AN+DN) term using three paramagnetic probes. The linear regression coefficient calculated for 15 different solvents was approximately 0.9, quite similar to those of other well-known polarity parameters, attesting to the validity of the (AN+DN) term as a novel "two-parameter" solvent polarity scale.

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Monitoring the Chemical Assembly of a Transmembrane Bradykinin Receptor Fragment: Correlation Between Resin Solvation, Peptide Chain Mobility, and Rate of Coupling

et al. 2002

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A combined resin solvation-peptide chain motion and kinetics of coupling reaction approach was applied to monitor details of the synthesis of TM-34, a 34-residue transmembrane segment of the bradykinin receptor. The dynamics of resinbound peptide fragments attached to a stable free radical amino acid were examined by EPR spectroscopy. In agreement with an abrupt decrease (from 83 to 43%) in peptide purity occurring in the 12−16 region when DMF was used, a much more strongly immobilized chain population was detected, especially at the 12-mer stage. Conversely, faster

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Solvation of polymers as model for solvent effect investigation: proposition of a novel polarity scale

Cited by 71 publications

References 65 publications

Ion channel-like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers

Ion channel-like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers

Application of Electron Paramagnetic Resonance Spectroscopy for Validation of the Novel (AN+DN) Solvent Polarity Scale

Monitoring the Chemical Assembly of a Transmembrane Bradykinin Receptor Fragment: Correlation Between Resin Solvation, Peptide Chain Mobility, and Rate of Coupling

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