The complexity of condensed tannin binding to bovine serum albumin – An isothermal titration calorimetry study

Kilmister, Rachel; Faulkner, Peta; Downey, Mark O.; Darby, Samuel J.; Falconer, Robert J.

doi:10.1016/j.foodchem.2015.04.144

Cited by 44 publications

(47 citation statements)

References 31 publications

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“…Given that a positive ΔS value may be associated with the first stage of binding interaction, 41, 42 where the ligand and enzyme are immobilized in a hydrophobic environment, we further examined the hydrophobic alteration of the α -glucosidase enzyme.…”

Section: Resultsmentioning

confidence: 99%

Structure activity related, mechanistic, and modeling studies of gallotannins containing a glucitol-core and α-glucosidase

Niesen

Cai

et al. 2015

RSC Adv.

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Gallotannins containing a glucitol core, which are only produced by members of the maple (Acer) genus, are more potent α-glucosidase inhibitors than the clinical drug, acarbose. While this activity is influenced by the number of substituents on the glucitol core (e.g. more galloyl groups leads to increased activity), the mechanisms of inhibitory action are not known. Herein, we investigated ligand-enzyme interactions and binding mechanisms of a series of ‘glucitol-core containing gallotannins (GCGs)’ against the α-glucosidase enzyme. The GCGs included ginnalins A, B and C (containing two, one, and one galloyl/s, respectively), maplexin F (containing 3 galloyls) and maplexin J (containing 4 galloyls). All of the GCGs were noncompetitive inhibitors of α-glucosidase and their interactions with the enzyme were further explored using biophysical and spectroscopic measurements. Thermodynamic parameters (by isothermal titration calorimetry) revealed a 1:1 binding ratio between GCGs and α-glucosidase. The binding regions between the GCGs and α-glucosidase, probed by a fluorescent tag, 1,1′-bis(4-anilino-5-napththalenesulfonic acid, revealed that the GCGs decreased the hydrophobic surface of the enzyme. In addition, circular dichroism analyses showed that the GCGs bind to α-glucosidase and lead to loss of the secondary α-helix structure of the protein. Also, molecular modeling was used to predict the binding site between the GCGs and the α-glucosidase enzyme. This is the first study to evaluate the mechanisms of inhibitory activities of gallotannins containing a glucitol core on α-glucosidase.

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Section: Resultsmentioning

confidence: 99%

Structure activity related, mechanistic, and modeling studies of gallotannins containing a glucitol-core and α-glucosidase

Niesen

Cai

et al. 2015

RSC Adv.

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“…However, through information obtained from alternative studies, it is generally accepted that CT-protein complex formation involves both hydrophobic (water-hating) and hydrogen-bonding interactions working in concert in the formation of the complex (Oh et al, 1980;Haslam, 1996;Cala et al, 2010;Kilmister et al, 2016). Research suggests that complexation is initiated through hydrophobic interactions between the CT and protein such as proline-rich proteins (Oh et al, 1980;Haslam, E., 1996;Kilmister et al, 2016) and protein segments (Baxter et al, 1997), as well as between protein aromatic groups such as tryptophan (Brás et al, 2010) and aromatic rings of the CTs. Water molecules surrounding the water-solubilizing groups in proteins are tightly bound and highly ordered via hydrogen bonds, whereas waters of hydration are more loosely bound and less ordered in hydrophobic regions (Haslam, 1996).…”

Section: Selectivity In the Formation Of Condensed Tannin-protein Commentioning

confidence: 99%

“…Unfortunately, a crystal structure of a CTprotein complex has not yet been accomplished, although a co-crystal structure of the protein transthyretin with the green tea flavan-3-ol epigallocatechin gallate has been reported (Miyata et al, 2010). However, through information obtained from alternative studies, it is generally accepted that CT-protein complex formation involves both hydrophobic (water-hating) and hydrogen-bonding interactions working in concert in the formation of the complex (Oh et al, 1980;Haslam, 1996;Cala et al, 2010;Kilmister et al, 2016). The first event that must take place before the formation of a CT-protein complex is displacement of the hydration layer surrounding the soluble protein.…”

Section: Selectivity In the Formation Of Condensed Tannin-protein Commentioning

confidence: 99%

“…Water molecules surrounding the water-solubilizing groups in proteins are tightly bound and highly ordered via hydrogen bonds, whereas waters of hydration are more loosely bound and less ordered in hydrophobic regions (Haslam, 1996). Research suggests that complexation is initiated through hydrophobic interactions between the CT and protein such as proline-rich proteins (Oh et al, 1980;Haslam, E., 1996;Kilmister et al, 2016) and protein segments (Baxter et al, 1997), as well as between protein aromatic groups such as tryptophan (Brás et al, 2010) and aromatic rings of the CTs. Evidence for hydrophobic interactions driving the CT complex includes significant proton nuclear magnetic resonance ( 1 H NMR) chemical shift differences occurring within protons of hydrophobic residues of a 19-residue proline-rich protein (Baxter et al, 1997) and gramicidin S (Zhang et al, 2002) during complexation with a select group of flavan-3-ol monomers and dimers.…”

Section: Selectivity In the Formation Of Condensed Tannin-protein Commentioning

confidence: 99%

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Activity, Purification, and Analysis of Condensed Tannins: Current State of Affairs and Future Endeavors

Zeller

2019

Crop Science

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As a class of plant polyphenolic compounds contained in some forages (i.e., sainfoin [Onobrychis viciifolia Scop.], big trefoil [Lotus pedunculatus Cav.], birdsfoot trefoil [Lotus corniculatus L.]), condensed tannins (CTs), also referred to as proanthocyanidins (PAs or PACs), exhibit a variety of biological effects on ruminants. The potential positive impact of CTs on the agricultural industry stems from their ability to modulate proteolysis during forage conservation and ruminal digestion, to prevent bloat, to reduce intestinal parasite burdens, to abate methane and ammonia emissions from ruminants, and to inhibit the activity of soil‐nitrifying bacteria. How CTs exert these effects on ruminants focuses on the interaction of CTs with proteins. The structure‐activity relationship in CT–protein interaction is not well understood but is known to be dependent on the structure and properties of both the CT and the protein. The purpose of this perspective is fivefold. First, we provide the reader with a better understanding of the structural diversity of CTs present in plant material and enable the reader to appreciate that not all CTs are the same. Second, we provide examples of how CT structural diversity affects the interaction of CTs with the protein, which, in turn, dictates the biological response from the animal. Third, we describe the hurdles in obtaining highly pure and well‐characterized CTs from natural sources for use in studies to attempt to elucidate how CTs impart each biological effect. We then describe improved and emerging techniques for CT analysis and, finally, we conclude this perspective with questions to address in future investigations and forward a list of recommendations for CT researchers to follow.

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“…The contribution from TDS during binding under aqueous conditions is difficult to interpret. It has been suggested in ITC studies of tannins binding to proteins that TDS has a systematic error, as any endothermic interaction subtracts from the exothermic heat changes detected by the ITC [26]. It has also been suggested that TDS is not a measure of how ordered the system is and it should be taken as a measure of energy dispersal [27].…”

Section: Resultsmentioning

confidence: 99%

An isothermal titration calorimetry study of phytate binding to lysozyme

Darby

Platts

Daniel

et al. 2016

J Therm Anal Calorim

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Isothermal titration calorimetry (ITC) was used to detect phytate binding to the protein lysozyme. This binding interaction was driven by electrostatic interaction between the positively charged protein and negatively charged phytate. When two phytate molecules bind to the protein, the charge on the protein is neutralised and no further binding occurs. The stoichiometry of binding provided evidence of phytate-lysozyme complex formation that was temperature dependent, being most extensive at lower temperatures. The initial stage of phytate binding to lysozyme was less exothermic than later injections and had a stoichiometry of 0.5 at 313 K, which was interpreted as phytate crosslinking two lysozyme molecules with corresponding water displacement. ITC could make a valuable in vitro assay to understanding binding interactions and complex formation that normally occur in the stomach of monogastric animals and the relevance of drinking water temperature on the extent of phytate-protein interaction. Interpretation of ITC data in terms of cooperativity is also discussed.

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The complexity of condensed tannin binding to bovine serum albumin – An isothermal titration calorimetry study

Cited by 44 publications

References 31 publications

Structure activity related, mechanistic, and modeling studies of gallotannins containing a glucitol-core and α-glucosidase

Structure activity related, mechanistic, and modeling studies of gallotannins containing a glucitol-core and α-glucosidase

Activity, Purification, and Analysis of Condensed Tannins: Current State of Affairs and Future Endeavors

An isothermal titration calorimetry study of phytate binding to lysozyme

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