Towards high resolution <sup>1</sup>H NMR spectra of tannin colloidal aggregates

Mirabel, Marie; Glories, Yves; Pianet, Isabelle; Dufourc, Érick J.

doi:10.1051/jcp:1999241

Cited by 8 publications

(6 citation statements)

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“…The spectra agree reasonably with those of catechin and epicatechin standards, as shown by each of the three expanded regions corresponding to the B, A and C rings (Fig. 3b), and with those published by Berregi et al (2003) and Mirabel et al (1999).…”

Section: Enzyme Activitysupporting

confidence: 84%

Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Gargouri

Manigand

Mauge

et al. 2009

Acta Crystallogr D Biol Crystallogr

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Together with leucoanthocyanidin reductase, anthocyanidin reductase (ANR) is one of the two enzymes of the flavonoid-biosynthesis pathway that produces the flavan-3-ol monomers required for the formation of proanthocyanidins or condensed tannins. It has been shown to catalyse the double reduction of anthocyanidins to form 2R,3R-flavan-3-ols, which can be further transformed to the 2S,3R isomers by non-enzymatic epimerization. ANR from grape (Vitis vinifera) was expressed in Escherichia coli and purified. Unexpectedly, RP-HPLC, LC-MS and NMR experiments clearly established that the enzyme produces a 50:50 mixture of 2,3-cis and 2,3-trans flavan-3-ols which have been identified by chiral chromatography to be 2S,3S- and 2S,3R-flavan-3-ols, i.e. the naturally rare (+)-epicatechin and (-)-catechin, when cyanidin is used as the substrate of the reaction. The first three-dimensional structure of ANR is described at a resolution of 2.2 A and explains the inactivity of the enzyme in the presence of high salt concentrations.

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Section: Enzyme Activitysupporting

confidence: 84%

Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Gargouri

Manigand

Mauge

et al. 2009

Acta Crystallogr D Biol Crystallogr

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“…In these conditions, no precipitate could be detected by visual inspection. However, NMR experiments were recorded using the HRMAS technology to take care of the colloidal behavior of these complexes that would otherwise lead to poorly resolved spectra (56).…”

Section: Resultsmentioning

confidence: 99%

Three-Dimensional Structure and Dynamics of Wine Tannin−Saliva Protein Complexes. A Multitechnique Approach

et al. 2003

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The interactions between the B3 (catechin-4alpha,8-catechin) red wine tannin and the human salivary protein fragment IB7(14) (SPPGKPQGPPPQGG) were monitored by (1)H magic angle spinning NMR, circular dichroism, electrospray ionization mass spectrometry, and molecular modeling. It is found that the secondary structure of IB7(14) is made of a type II helix (collagen helix) and random coil. The central glycine 8 appears to act as a flexible rotula separating two helix II regions. Three tannin molecules tightly complex the peptide, without modifying its secondary structure, but seem to reduce its conformational dynamics. The binding dissociation constant is in the millimolar range. B3 tannins with a "tweezers" conformation bind to the hydrophilic side of the saliva peptide, suggesting that the principal driving forces toward association are governed by hydrogen bonding between the carbonyl functions of proline residues and both the phenol and catechol OH groups. These findings are further discussed in the frame of an astringency phenomenon.

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“…100 mM) in the presence of 10% ethanol as previously described. 29 The differences observed between procyanidin monomers (mainly catechin and epicatechin with the case of EGCG, which is clearly neither a monomer nor a dimer, being taken aside at the moment) and oligomers should be explained by both their 3D structures and levels of hydration. Monomers, which have a lower level of hydration than do dimers/trimers, have a relatively planar structure favoring intermolecular stacking, affording the possibility to form larger and larger micelles that are able to coalesce to form hazes or even precipitates.…”

Section: Discussionmentioning

confidence: 96%

Modeling Procyanidin Self-Association Processes and Understanding Their Micellar Organization: A Study by Diffusion NMR and Molecular Mechanics

et al. 2008

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The colloidal behavior of eight synthetic procyanidins (three monomers, four dimers, and a trimer) has been investigated in water or in a winelike medium using DOSY NMR spectroscopy and molecular dynamics simulations. Different behavior was observed for monomers and oligomers. Monomers self-associate with a high affinity constant (37-53 M(-1)) to form micelles at low cmc (critical micelle concentration) values (1-5 g.L(-1)). These micelles undergo a time-dependent coalescence process to form hazes and precipitates. As for dimers and the trimer, self-association also occurs but with a lower affinity (approximately 6 M(-1)) and at higher cmc values (10-20 g.L(-1)) to form small micelles (<5 nm) that remain stable throughout the experiment. The presence of 10% ethanol does not significantly affect the self-association constant for monomers and oligomers but increases their cmc values by approximately 50% and decreases the micelle size by a factor 2. However, the presence of 20 mM NaCl appears to negate the effect of ethanol. This study helps to clarify the role of procyanidin monomers versus oligomers in wine turbidity and demonstrates that procyanidin oligomers are fully available to interact with saliva proteins.

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Towards high resolution ¹H NMR spectra of tannin colloidal aggregates

Cited by 8 publications

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Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Three-Dimensional Structure and Dynamics of Wine Tannin−Saliva Protein Complexes. A Multitechnique Approach

Modeling Procyanidin Self-Association Processes and Understanding Their Micellar Organization: A Study by Diffusion NMR and Molecular Mechanics

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Towards high resolution 1H NMR spectra of tannin colloidal aggregates

Cited by 8 publications

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Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Structure and epimerase activity of anthocyanidin reductase fromVitis vinifera

Three-Dimensional Structure and Dynamics of Wine Tannin−Saliva Protein Complexes. A Multitechnique Approach

Modeling Procyanidin Self-Association Processes and Understanding Their Micellar Organization: A Study by Diffusion NMR and Molecular Mechanics

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Towards high resolution ¹H NMR spectra of tannin colloidal aggregates