Molecular Model for Astringency Produced by Polyphenol/Protein Interactions

Jöbstl, Elisabeth; O'Connell, J E A; Fairclough, J. Patrick A.; Williamson, Michael P.

doi:10.1021/bm0345110

Cited by 300 publications

(250 citation statements)

References 46 publications

Supporting

Mentioning

233

Contrasting

Unclassified

Order By: Relevance

“…S-11). In conclusion, these and previously published results point to EGCG as a generic binder [34][35][36][37][38][39][40][41][42] and modulator 41,42 of protein structure.…”

Section: Egcg Binding Promotes As Compactionsupporting

confidence: 79%

Opposite Structural Effects of Epigallocatechin-3-gallate and Dopamine Binding to α-Synuclein

et al. 2016

View full text Add to dashboard Cite

The intrinsically disordered and amyloidogenic protein -synuclein (AS) has been linked to several neurodegenerative states, including Parkinson's disease. Here, nano-electrospray-ionization mass spectrometry (nano-ESI-MS), ion mobility (IM), and native top-down electron transfer dissociation (ETD) techniques are employed to study AS interaction with small molecules known to modulate its aggregation, such as epigallocatechin-3-gallate (EGCG) and dopamine (DA). The complexes formed by the two ligands under identical conditions reveal peculiar differences. While EGCG engages AS in compact conformations, DA preferentially binds to the protein in partially extended conformations. The two ligands also have different effects on AS structure as assessed by IM, with EGCG leading to protein compaction and DA to its extension. Native top-down ETD on the protein-ligand complexes shows how the different observed modes of binding of the two ligands could be related to their known opposite effects on AS aggregation. The results also show that the protein can bind either ligand in the absence of any covalent modifications, such as e.g. oxidation.

show abstract

“…S-11). In conclusion, these and previously published results point to EGCG as a generic binder [34][35][36][37][38][39][40][41][42] and modulator 41,42 of protein structure.…”

Section: Egcg Binding Promotes As Compactionsupporting

confidence: 79%

Opposite Structural Effects of Epigallocatechin-3-gallate and Dopamine Binding to α-Synuclein

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The observed bulk aggregation behaviour shares similarity with the "three stage binding model" previously proposed by Jöbstl et al [3], elaborated through studying EGCG-casein complexes. The main similarity stems from the fact that EGCG binding to mucin promotes the association of polyphenol-glycoprotein complexes resulting in the formation of aggregates.…”

Section: Analysis Of Egcg-mucin Aggregationsupporting

confidence: 85%

“…Bioavailability of dietary polyphenols may not be a universal predictor of their physiological efficacy; other factors such as polyphenol ability to bind both mucins (which line the GIT) and dietary polysaccharides may play dominant roles. In addition, polyphenols are known to influence the physicochemical state of several common dietary components such as dairy proteins including caseins [3]. They are also implicated in the perception of astringency [4][5][6][7][8][9][10][11][12], a complex mouthfeel effect, which has marked effects on the perception of foods and beverages [13].…”

Section: Introductionmentioning

confidence: 99%

Surface rearrangement of adsorbed EGCG–mucin complexes on hydrophilic surfaces

Horváth

Yakubov

Ramsden

2017

International Journal of Biological Macromolecules

View full text Add to dashboard Cite

The kinetic adsorption-desorption behaviour of porcine gastric mucin in the presence of physiologically relevant concentrations of the polyphenol epigallocatechin gallate (EGCG) was investigated using high-resolution kinetic optical waveguide lightmode spectroscopy (OWLS) and atomic force microscopy (AFM). Comparison with dynamic light scattering results from EGCGmucin mixtures indicates that discrete particles are formed whose size increases with increasing EGCG:mucin ratio. These particles are deduced to be the adsorbing entities, which fuse on the surface to form complex surface layers. At low molar EGCG:mucin ratios (< 1000), aggregates fuse on the surface to form a monolayer similar to one of pure mucin. With increasing EGCG concentration, the surface assembly of aggregates becomes consistent with their rearrangement and spreading in the shape of a spherical segment. At the highest molar ratios investigated (> 12 000) the particles begin to destabilize. The presence of EGCG leads to birefringence hysteresis during adsorption-desorption, indicating structural rearrangement, even at molar ratios 1000. The intensification of the phenomenon with increasing EGCG:mucin ratio mimics what was previously observed with the increase of mucin concentration in an EGCG-free system.

show abstract

“…O processo de purificação da caseína por desfosforilação afeta negativamente a coesão estrutural e a capacidade de formação de estruturas micelares, originalmente observadas na caseína bruta. Como conseqüência, há um aumento da superfície reacional e uma maior capacidade de complexar taninos, porém, à custa de um aumento da hidrofobia da superfície 13,14 . Em caseínas brutas, as propriedades de superfície são influenciadas pelas κ-e α S -caseínas presentes na superfície das micelas 14 .…”

Section: Resultsunclassified

Avaliação das variáveis analíticas do método de Folin-Ciocalteu para determinação do teor de taninos totais utilizando como modelo o extrato aquoso de folhas de psidium guajava L.

Verza¹,

Kreinecker²,

Reis³

et al. 2007

Quím. Nova

View full text Add to dashboard Cite

Psidium guajava L. LEAVES AQUEOUS EXTRACT AS A MODEL. The main analytical variables of a modified Folin-Ciocalteu method were studied by UV-Vis and gradient HPLC-PDA methods, using purified (PC) and technical grade (TGC) casein. Rutin and an aqueous extract of Psidium guajava L. leaves were used as models. The best results were ascribed to TGC. Certainly PC bonds the polyphenols of the P. guajava extract better than TGC, but TGC afforded better precision. A lack of specificity occurred when rutin was analyzed together with the P guajava extract. Additional analyses performed with the flavonoid fraction of P. guajava extract by HPLC-PDA had confirmed that casein was able to bind catechin, gallic acid and P. guajava flavonoids in a non-specific way.Keywords: tannins; casein; hide powder. INTRODUÇÃOAtualmente, os principais métodos para determinação do teor de taninos abrangem a cromatografia líquida de alta eficiência (CLAE) e a espectrofotometria. Os métodos espectrofotométricos mais aceitos envolvem a complexação prévia dos taninos com substratos protéicos (pó-de-pele, caseína, albumina) ou poliméricos (PVPP). Em todas as suas variantes, os métodos por oxi-redução derivam, basicamente, da proposta de quantificação do ácido úrico por Folin e Macallum 1 , mais tarde modificado para polifenóis 2 . Nestes, os polifenóis reagem com reagentes de oxi-redução específicos, formando um complexo de coloração azul, passível de ser quantificado por espectrofotometria no visível. Conseqüentemente, a reação não é específica para taninos. Uma forma de contornar essa falta de especificidade é retirando os taninos do meio mediante adsorção com substratos protéicos. Assim, o teor de taninos é calculado como a diferença entre o teor de polifenóis totais e teor da fração polifenólica não-adsorvida 3-5 . Vários métodos espectrofotométricos atualmente aplicados a drogas vegetais foram desenvolvidos em um marco regulatório diferente do atual, tendo-se desenvolvido a partir do reagente de Folin e Macallum. Diferentes Farmacopéias e Códigos Oficiais determinam condições de análise distintas ao longo dos anos. Isso não necessariamente parece ter implicado a validação específica dos mesmos como métodos gerais ou específicos. Isso inclui o método de determinação do teor de taninos totais, baseado no uso de pó-de-pele e caseína como agentes complexantes. No presente trabalho, foram avaliadas as principais variáveis analíticas, com ênfase na especificidade da caseína frente à presença simultânea de flavonóides no meio reacional. Com esse intuito, rutina e Psidium guajava foram selecionados como substância e extrato modelo.Nos métodos por CLAE o reagente de Folin-Ciocalteu não é utilizado. No entanto, esse tipo de método foi empregado nesse trabalho com fins de caracterização do extrato vegetal de Psidium guajava. A utilização dessa técnica com fins analíticos foi desconsiderada no presente trabalho, partindo-se do pressuposto que a quantificação de polifenóis individuais não reflete a parcela polimérica dos taninos. PARTE EXPERIMENTAL Solvent...

show abstract

Molecular Model for Astringency Produced by Polyphenol/Protein Interactions

Cited by 300 publications

References 46 publications

Opposite Structural Effects of Epigallocatechin-3-gallate and Dopamine Binding to α-Synuclein

Opposite Structural Effects of Epigallocatechin-3-gallate and Dopamine Binding to α-Synuclein

Surface rearrangement of adsorbed EGCG–mucin complexes on hydrophilic surfaces

Avaliação das variáveis analíticas do método de Folin-Ciocalteu para determinação do teor de taninos totais utilizando como modelo o extrato aquoso de folhas de psidium guajava L.

Contact Info

Product

Resources

About