Vibrational circular dichroism of gramicidin D in organic solvents

Zhao, Chunxia; Polavarapu, Prasad L.

doi:10.1002/(sici)1520-6343(1999)5:5<276::aid-bspy2>3.0.co;2-8

Cited by 13 publications

(23 citation statements)

References 37 publications

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“…35 In each case, a positive VCD couplet was observed in the amide I region with a negative VCD component near 1650 cm −1 and a positive VCD component near 1632 cm −1 , similar to the VCD spectrum of ␤ Leu in Fig. 2͑a͒.…”

Section: Discussionsupporting

confidence: 66%

“…2͑b͔͒ are essentially identical to those that we measured previously for these peptides; 14 in addition, the two spectra are very similar to each other, indicating that the IR features in the amide I and II regions primarily originate from common structural elements of the peptides. The IR spectra also resemble those of gD acquired in dioxane, where the lefthanded ↑↓␤ 5.6 -helical dimer predominates; 35 in particular, the largest peak in the amide I region appears at approximately 1635 cm −1 for all three peptides. For comparison, Naik and Krimm calculated a value of 1636 cm −1 for the amide I band of an idealized ↑↓␤ 5.6 helix.…”

Section: Resultsmentioning

confidence: 63%

“…The dominant feature of the VCD spectrum of ␤ Leu is a positive VCD couplet, with a negative VCD component near 1650 cm −1 and a positive VCD component near 1632 cm −1 , which are close to the respective peak positions observed for gD in dioxane. 35 The VCD bands in the amide II region for ␤ Leu also resemble those of gD in dioxane, 35 with a weaker negative VCD couplet having a positive VCD component near 1550 cm −1 and a negative VCD component near 1520 cm −1 . Unlike gD, however, ␤ Leu also shows a small positive VCD couplet at higher frequency, with a negative component near 1690 cm −1 and a positive component near 1670 cm −1 .…”

Section: 37mentioning

confidence: 87%

“…35,[38][39][40] Gramicidin D comprises gramicidins A, B, and C, which vary slightly in their sequence but are nearly functionally equivalent. This chemical heterogeneity, together with the aforementioned tendency of gD to exist in solution as a mixture of species ͑ss, ds, parallel, antiparallel, etc.͒, has led experimentalists to vary the solvent to favor the relative population of different species in solution.…”

Section: Discussionmentioning

confidence: 99%

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Vibrational circular-dichroism spectroscopy of homologous cyclic peptides designed to fold into β helices of opposite chirality

et al. 2011

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Cyclic ␤-helical peptides have been developed as model structured biomolecules for examining peptide adsorption and conformation on surfaces. As a key prerequisite to circular-dichroism ͑CD͒ analysis of these model peptides on surfaces, their conformations and the corresponding vibrational spectra in the 1400-1800 cm −1 range were analyzed by vibrational circular-dichroism ͑VCD͒ spectroscopy in solution. The two model peptides ͑"␤ Leu and ␤ Val"͒ were examined in chloroform, where they each fold into a homogeneous well-defined antiparallel double-stranded ␤-helical species, as determined previously by NMR and electronic CD spectroscopy. Because the ␤-helical conformations of ␤ Leu and ␤ Val are well characterized, the VCD spectra of these peptides can be unambiguously correlated with their structures. In addition, these two ␤-helical peptides differ from one another in two key respects that make them uniquely advantageous for CD analysis-first, while their backbone conformations are topologically similar, ␤ Leu and ␤ Val form helices of opposite chiralities; second, the two peptides differ in their sequences, i.e., composition of the side chains attached to the backbone. The observed VCD spectra for ␤ Leu and ␤ Val are roughly mirror images of each other, indicating that the VCD features are dominated by the chirality and conformation of the peptide backbone rather than by the peptide sequence. Accordingly, spectra similarly characteristic of peptide secondary structure can be expected for peptides designed to be structural analogs of ␤ Leu and ␤ Val while incorporating a variety of side chains for studies of surface adsorption from organic and aqueous solvents.

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Section: Discussionsupporting

confidence: 66%

Section: Resultsmentioning

confidence: 63%

Section: 37mentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

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Vibrational circular-dichroism spectroscopy of homologous cyclic peptides designed to fold into β helices of opposite chirality

et al. 2011

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“…In subsequent work, we designed a polar cyclic ↑↓ β 5.6 ‐helical peptide, cyclo[( d ‐Ala– l ‐Glu– d ‐Leu– l ‐Lys– d ‐Val– l ‐Thr– d ‐Leu– l ‐Thr– d ‐Ala– l ‐Pro–Gly– d ‐Leu– l ‐Glu– d ‐Val– l ‐Arg– d ‐Leu– l ‐Thr– d ‐Ala– l ‐Thr– d ‐Val– l ‐Pro–Gly)–] ( WS β ), that folds stably in MeOH (Figure (C))—a solvent in which gA is both conformationally polymorphic and partially unfolded. In the present work, we further advance the field of β ‐helical foldamers by showing that peptides Leu β , Val β , and WS β are all fully β ‐helical in TFE—a solvent in which gA is unstructured .…”

Section: Introductionmentioning

confidence: 89%

Synthesis and characterization of cyclic peptides that are β -helical in trifluoroethanol

et al. 2014

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We show that three designed cyclic d,l-peptides are β-helical in TFE-a solvent in which the archetypal β-helical peptide, gA, is unstructured. This result represents an advance in the field of β-helical peptide foldamers and a step toward achieving β-helical structure under a broad range of solvent conditions. We synthesized two of the three peptides examined using an improved variant of our original CBC strategy. Here, we began with a commercially available PEG-PS composite resin prefunctionalized with the alkanesulfonamide 'SCL' linker and preloaded with glycine. Our new conditions avoided C-terminal epimerization during the CBC step and simplified purification. In addition, we present results to define the scope and limitations of our CBC strategy. These methods and observations will prove useful in designing additional cyclic β-helical peptides for applications ranging from transmembrane ion channels to ligands for macromolecular targets. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

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Noncovalent interactions of peptides with porphyrins in aqueous solution: Conformational study using vibrational CD spectroscopy

Urbanová

Setnička²,

Král³

et al. 2001

Biopolymers

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Noncovalent interactions of poly(L‐lysine) (PL), oligopeptides L‐lysyl‐L‐alanyl‐L‐alanine and (L‐lysyl‐L‐alanyl‐L‐alanine)2 with meso‐tetrakis(4‐sulfonatophenyl)porphine (TPPS), and poly(L‐glutamic acid) (PLGA) with meso‐tetrakis(1‐methyl‐4‐pyridyl)porphine tetra‐p‐tosylate (TMPyP) in aqueous solutions have been studied using combination of spectroscopic methods: Vibrational circular dichroism (VCD) spectroscopy in the mid‐infrared region provides a direct information on conformational changes of the polypeptides and oligopeptides caused by interactions with porphyrins; ultraviolet‐visible absorption, fluorescence, and electronic circular dichroism (ECD) reveal the aggregation characterization of the porphyrin part of the complexes. Interactions of TPPS with tripeptide, hexapeptide, and PL containing about ten amino acid residues in the molecular chain are accompanied with the changes of VCD patterns in the amide I′ region. In these cases, the conformation of the oligopeptide part of complexes is obviously influenced by interactions with TPPS and partial changes of random coil structure are observed in VCD. When PL was composed of the hundreds of lysine residues, just a weak intensity decrease was detected and the shape of VCD spectrum typical for the random coil structure was preserved. As follows from the uv‐vis absorption and fluorescence spectra, porphyrin molecules are attached to peptides by electrostatic interaction as a monomer or dimer and interaction between porphyrin and peptide depends on the polypeptide chain length. For the PLGA‐TMPyP system with PLGA containing from tens to hundreds of glutamic acid residues in the chain, the VCD spectra were unchanged when TMPyP was presented in the aqueous solution of PLGA and random coil conformation of PLGA‐TMPyP aggregates was preserved. © 2001 John Wiley & Sons, Inc. Biopolymers (Pept Sci) 60: 307–316, 2001

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Vibrational circular dichroism of gramicidin D in organic solvents

Cited by 13 publications

References 37 publications

Vibrational circular-dichroism spectroscopy of homologous cyclic peptides designed to fold into β helices of opposite chirality

Vibrational circular-dichroism spectroscopy of homologous cyclic peptides designed to fold into β helices of opposite chirality

Synthesis and characterization of cyclic peptides that are β -helical in trifluoroethanol

Noncovalent interactions of peptides with porphyrins in aqueous solution: Conformational study using vibrational CD spectroscopy

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