Conformational studies of TOAC-labeled bradykinin analogues in model membranes

Vieira, Renata F. F.; Casallanovo, Fábio; Cilli, Eduardo Maffud; Paiva, A. C. M.; Schreier, Shirley; Nakaie, Clóvis R.

doi:10.1007/bf02576869

Cited by 7 publications

(6 citation statements)

References 36 publications

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“…In contrast, the spectra show that the TFE‐stabilized turns in BK and TOAC 0 ‐BK are different from that in TOAC 3 ‐BK (Figure 4, Table II). Moreover, the CD spectra of BK and its spin‐labeled derivatives in TFE closely resemble those obtained upon binding the peptides to sodium dodecyl sulfate (SDS) micelles 37. NMR studies of SDS‐bound native BK indicate that a β‐turn is formed in the peptide C‐terminus, but that the N‐terminal portion retains a certain degree of flexibility 71, 72.…”

Section: Discussionmentioning

confidence: 71%

“…While the internally labeled analogues had no detectable biological activity, the N‐terminally labeled hormones presented significant potency in different muscle preparations 36. A preliminary account of the spectroscopic properties of these peptides was presented,35 as well as studies of the interaction of BK and its TOAC derivatives with model membranes 37…”

Section: Introductionmentioning

confidence: 99%

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Conformational basis for the biological activity of TOAC‐labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

et al. 2004

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N-Terminally and internally labeled analogues of the hormones angiotensin (AII, DRVYIHPF) and bradykinin (BK, RPPGFSPFR) were synthesized containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC). TOAC replaced Asp1 (TOAC1-AII) and Val3 (TOAC3-AII) in AII and was inserted prior to Arg1 (TOAC0-BK) and replacing Pro3 (TOAC3-BK) in BK. The peptide conformational properties were examined as a function of trifluoroethanol (TFE) content and pH. Electron paramagnetic resonance spectra were sensitive to both variables and showed that internally labeled analogues yielded rotational correlation times (tauC) considerably larger than N-terminally labeled ones, evincing the greater freedom of motion of the N-terminus. In TFE, tauC increased due to viscosity effects. Calculation of tau(Cpeptide)/tau(CTOAC) ratios indicated that the peptides acquired more folded conformations. Circular dichroism spectra showed that, except for TOAC1-AII in TFE, the N-terminally labeled analogues displayed a conformational behavior similar to that of the parent peptides. In contrast, under all conditions, the TOAC3 derivatives acquired more restricted conformations. Fluorescence spectra of AII and its derivatives were especially sensitive to the ionization of Tyr4. Fluorescence quenching by the nitroxide moiety was much more pronounced for TOAC3-AII. The conformational behavior of the TOAC derivatives bears excellent correlation with their biological activity, since, while the N-terminally labeled peptides were partially active, their internally labeled counterparts were inactive [Nakaie, C. R., et al., Peptides 2002, 23, 65-70]. The data demonstrate that insertion of TOAC in the middle of the peptide chain induces conformational restrictions that lead to loss of backbone flexibility, not allowing the peptides to acquire their receptor-bound conformation.

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Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Conformational basis for the biological activity of TOAC‐labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

et al. 2004

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“…Combined EPR and CD studies were also performed on the interaction of BK (Vieira et al 2002 ) and AII (Vieira et al 2009 ) and their TOAC-labeled analogues with detergent micelles—negatively charged SDS and zwitterionic HPS. Line broadening in the EPR spectra indicated micelle binding (Fig.…”

Section: Biologically Active Peptides: Ligands and Fragments Of G Promentioning

confidence: 99%

The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

et al. 2012

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We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future.

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“…A potencialidade do uso do TOAC foi inclusive avaliada em artigo específico na seção de ciência e inovação da revista Chemical Engeneering News, publicada pela American Chemical Society 74 , com especial destaque para a importância da participação de nosso grupo na inserção do TOAC na química de peptídeos e polímeros. Dentre os inúmeros estudos desenvolvidos até o momento na literatura, é possível observar o emprego desse marcador, por exemplo, para estudos conformacionais e de função biológica da bradicinina (BK), a qual foi marcado com TOAC na posição zero e três, e estudos espectrais por RPE e dicroísmo circular (CD), tanto em solução [75][76][77][78] quanto em micelas 79,80 . Estudo similar tem sido desenvolvido também com o peptídeo vasoativo AngII 65,76 .…”

Section: Estudo Estrutural E Funcional De Peptídeos Com Toacunclassified

Produção de peptídeos: aprimoramento da síntese em polímeros através do uso da ressonância paramagnética eletrônica (RPE)

Nakaie¹,

Malavolta²,

Schereier³

et al. 2017

Biotecnologia Aplicada À Agro&Indústria - Vol. 4

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Conformational studies of TOAC-labeled bradykinin analogues in model membranes

Cited by 7 publications

References 36 publications

Conformational basis for the biological activity of TOAC‐labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

Conformational basis for the biological activity of TOAC‐labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

Produção de peptídeos: aprimoramento da síntese em polímeros através do uso da ressonância paramagnética eletrônica (RPE)

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