Theoretical conformational analysis of Asn<sup>1</sup>, Val<sup>5</sup> angiotensin II

Coen, Jean-Louis De; Ralston, Evelyn

doi:10.1002/bip.1977.360160908

Cited by 46 publications

(29 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar results were obtained for TOAC 3 -AII at pHs 4.0 and 7.0 ( Figure 2B); also in this case, fluorescence and CD data did suggest a peptide-micelle interaction (see later). At pH 10.0, a two-component spectrum was obtained ( Figure 2B).…”

Section: Angiotensin and Toac-labeled Analogs In Micelles 527supporting

confidence: 89%

“…In addition, while broadening was seen in the spectra of TOAC 1 -AII at the lowest concentrations of the latter detergent, much below its critical micellar concentration (cmc, ca. 8 mM in pure water), this phenomenon only took place at approximately the cmc of SDS for TOAC 3 -AII. Moreover, below the detergent cmc, the spectra of TOAC 1 -AII show the presence of two components, the broad one corresponding to SDS-bound peptide and the narrow one corresponding to the peptide in the aqueous phase.…”

Section: Epr Studiesmentioning

confidence: 94%

“…The peptide is characterized by a high degree of flexibility and several structural models have been suggested based on theoretical calculations [3][4][5][6][7] and on different experimental approaches for the peptide in solution -in aqueous media and in the presence of secondary structure-inducing solvents [8][9][10]16,21,23,[26][27][28][29] and on binding to model membranes. 20,27,[30][31][32][33][34][35] Spectroscopic studies and theoretical calculations have led to the proposal of different conformations for AII in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

et al. 2009

View full text Add to dashboard Cite

The interaction between angiotensin II (AII, DRVYIHPF) and its analogs carrying 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) and detergents--negatively charged sodium dodecyl sulfate (SDS) and zwitterionic N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS)--was examined by means of EPR, CD, and fluorescence. EPR spectra of partially active TOAC1-AII and inactive TOAC3-AII in aqueous solution indicated fast tumbling, the freedom of motion being greater at the N-terminus. Line broadening occurred upon interaction with micelles. Below SDS critical micelle concentration, broader lines indicated complex formation with tighter molecular packing than in micelles. Small changes in hyperfine splittings evinced TOAC location at the micelle-water interface. The interaction with anionic micelles was more effective than with zwitterionic micelles. Peptide-micelle interaction caused fluorescence increase. The TOAC-promoted intramolecular fluorescence quenching was more pronounced for TOAC3-AII because of the proximity between the nitroxide and Tyr4. CD spectra showed that although both AII and TOAC1-AII presented flexible conformations in water, TOAC3-AII displayed conformational restriction because of the TOAC-imposed bend (Schreier et al., Biopolymers 2004, 74, 389). In HPS, conformational changes were observed for the labeled peptides at neutral and basic pH. In SDS, all peptides underwent pH-dependent conformational changes. Although the spectra suggested similar folds for AII and TOAC1-AII, different conformations were acquired by TOAC3-AII. The membrane environment has been hypothesized to shift conformational equilibria so as to stabilize the receptor-bound conformation of ligands. The fact that TOAC3-AII is unable to acquire conformations similar to those of native AII and partially active TOAC1-AII is probably the explanation for its lack of biological activity.

show abstract

Section: Angiotensin and Toac-labeled Analogs In Micelles 527supporting

confidence: 89%

Section: Epr Studiesmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

et al. 2009

View full text Add to dashboard Cite

show abstract

“…The method followed for the conformational analysis of the Ca-A23187 complex is based on a strategy described elsewhere (23) and currently used to study the conformations of polypeptides (23)(24)(25)(26) and other molecules (27,28). This method was modified to incorporate variations in the dielectric constant and the energy of transfer from one environment to another at the simulated lipid-water interface.…”

Section: Methodsmentioning

confidence: 99%

Conformational analysis of the calcium--A23187 complex at a lipid--water interface.

Brasseur¹,

Deleers²,

Malaisse³

et al. 1982

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

View full text Add to dashboard Cite

A possible conformation of the complex formed by one calcium ion and two molecules of the ionophore A23187 at a simulated lipid-water interface was predicted by a variant method for conformational analysis. This method takes into account, in addition to the Van der Waals energy, electrostatic interaction, and torsional potential, the alteration of electrostatic forces attributable to changes in dielectric constant at the interface and the transfer energy for each part of the complex as it moves through the lipid-water interface. The most probable conformer was characterized by a two-fold axial symmetry that was maintained during transition to the hydrophobic bulk conformation. Minor changes in the interfacial structure were sufficient to achieve the configuration characteristic of the hydrophobic bulk phase.Carboxylic ionophores such as A23187 and bromolasalocid are widely used to facilitate Ca2+ transport across natural (1-4) or artificial (5-9) membranes. These ionophores form complexes in which each Ca2+ is bound to two molecules of the same (10-12) or different (13-14) ionophores. The conformations of such complexes in nonpolar solvents and in the crystalline form have been extensively investigated (15)(16)(17)(18)(19)(20). However, to our knowledge, no information is available on the transient conformation of the complex when it is formed at a lipid-water interface. The stoichiometry of the complex and the pKa value have been established with liposomes and solvents of different polarity (6,8,15,21). By using a monolayer approach, Ferreira et aL (22) have examined the conformational stability (kd) and molecular area of A23187 at an air-water interface.In the present study, we have attempted to define the conformation of the complex between Ca2+ and two molecules of A23187 at a simulated lipid-water interface. For this purpose, we took into account for calculation of conformational energy not only the Van der Waals but also the electrostatic and torsional contributions. In addition, the electrostatic contributions were calculated as a function of changes in the dielectric constant, and allowance was made for the transfer energy of each part of the molecule as it moves through the lipid-water interface. METHODSThe method followed for the conformational analysis of the Ca-A23187 complex is based on a strategy described elsewhere (23) and currently used to study the conformations of polypeptides (23-26) and other molecules (27,28). This method was modified to incorporate variations in the dielectric constant and the energy of transfer from one environment to another at the simulated lipid-water interface.Briefly, the total conformational energy of the interfacial complex was empirically calculated as the sum of all contributions resulting from local interactions-i. e., the Van der Waals energy, the torsional potential, the electrostatic interaction, and the transfer energy. The electrostatic energy was calculated as a function of the dielectric constant (E). To simulate a lipid-water interface, the diel...

show abstract

“…Concerning angiotensin, a good correlation has been found42 between biological activity of 14 mono-substituted analogs and their ability to assume the most probable conformations described by De Coen and Ralston. 17 …”

Section: Conformation-activity Relationshipsmentioning

confidence: 97%

Titration and fluorometric studies of the tyrosine side chain of angiotensin II and related peptides

Juliano¹,

Laluce²,

Oliveira³

et al. 1979

Biopolymers

View full text Add to dashboard Cite

SynopsisThe effect of charged side chains on the ionization and fluorescence of the Tyr4 phenolic group in angiotensin (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) was investigated. Several synthetic peptides related to angiotensin were titrated spectrophotometrically and quantum yields of tyrosine fluorescence were also determined. The electrostatic interactions were interpreted according to the Kirkwood-Tanford theory, and the results were related to a recently proposed model [J. L. De Coen and E. Biopolyrners 16,19291 for angiotensin conformation in solution. The titration and fluorescence results are in good agreement with the folded conformations of this model, with the exception that the data indicate a weaker interaction between the histidine side chain and the C-terminal carboxyl groups than that proposed in the model.

show abstract

Theoretical conformational analysis of Asn¹, Val⁵ angiotensin II

Cited by 46 publications

References 19 publications

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

Conformational analysis of the calcium--A23187 complex at a lipid--water interface.

Titration and fluorometric studies of the tyrosine side chain of angiotensin II and related peptides

Contact Info

Product

Resources

About

Theoretical conformational analysis of Asn1, Val5 angiotensin II

Cited by 46 publications

References 19 publications

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

Conformational properties of angiotensin II and its active and inactive TOAC‐labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies

Conformational analysis of the calcium--A23187 complex at a lipid--water interface.

Titration and fluorometric studies of the tyrosine side chain of angiotensin II and related peptides

Contact Info

Product

Resources

About

Theoretical conformational analysis of Asn¹, Val⁵ angiotensin II