Dissociation and reduction of covalent β-lactoglobulin–quinone adducts by dithiothreitol, tris(2-carboxyethyl)phosphine, or sodium sulfite

Jongberg, Sisse; Lund, Marianne N.; Otte, Jeanette

doi:10.1016/j.ab.2015.02.008

Cited by 21 publications

(16 citation statements)

References 39 publications

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“…Again, especially the samples containing 1500 ppm 4MC stored under oxygen for 7 days showed a clearly lower band intensity for MHC and actin. However, a previous study of the Cys–4MC adduct formed between 4MC and β-lactoglobulin as the protein source showed that the Cys–4MC adduct was able to partly dissociate by treatment with DTT . Nevertheless, the present results indicated that the protein polymers were of nonreducible character.…”

Section: Resultscontrasting

confidence: 81%

Quantitation of Protein Cysteine–Phenol Adducts in Minced Beef Containing 4-Methyl Catechol

Arsad

Zainudin

Gobba

et al. 2020

J. Agric. Food Chem.

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Thiol groups of cysteine (Cys) residues in proteins react with quinones, oxidation products of polyphenols, to form protein–polyphenol adducts. The aim of the present work was to quantify the amount of adduct formed between Cys residues and 4-methylcatechol (4MC) in minced beef. A Cys–4MC adduct standard was electrochemically synthesized and characterized by liquid chromatography–mass spectrometry (LC–MS) as well as NMR spectroscopy. Cys–4MC adducts were quantified after acidic hydrolysis of myofibrillar protein isolates (MPIs) and LC–MS/MS analysis of meat containing either 500 or 1500 ppm 4MC and stored at 4 °C for 7 days under a nitrogen or oxygen atmosphere. The concentrations of Cys–4MC were found to be 2.2 ± 0.3 nmol/mg MPI and 8.1 ± 0.9 nmol/mg MPI in meat containing 500 and 1500 ppm 4MC, respectively, and stored for 7 days under oxygen. The formation of the Cys–4MC adduct resulted in protein thiol loss, and ca. 62% of the thiol loss was estimated to account for the formation of the Cys–4MC adduct for meat containing 1500 ppm 4MC. Furthermore, protein polymerization increased in samples containing 4MC as evaluated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), and the polymerization was found to originate from protein–polyphenol interactions as evaluated by a blotting assay with staining by nitroblue tetrazolium.

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Section: Resultscontrasting

confidence: 81%

Quantitation of Protein Cysteine–Phenol Adducts in Minced Beef Containing 4-Methyl Catechol

Arsad

Zainudin

Gobba

et al. 2020

J. Agric. Food Chem.

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“…33 The depletion of free thiols is a common consequence of the covalent binding of phenolics to protein residues. 34 Bae et al 35 reported that the incubation of EGCG with HSA occurred along with the loss on a free sulfhydryl group in HSA which supports the present hypothesis. As already explained, the nucleophilic addition leads to the regeneration of the hydroquinone which may display antioxidant properties due to the presence of hydroxyl groups.…”

Section: Papersupporting

confidence: 87%

Redox chemistry of the molecular interactions between tea catechins and human serum proteins under simulated hyperglycemic conditions

2016

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Carbonylation is an irreversible modification in oxidized proteins that has been directly related to a number of health disorders including Type 2 diabetes. Dietary antioxidants have been proposed to counteract the oxidative stress occurring under hyperglycemic conditions. An understanding of the nature and consequences of the molecular interactions between phytochemicals and human plasma proteins is of utmost scientific interest. Three tea catechins namely epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) were tested for (i) their affinity to bind to human serum albumin (HSA) and human hemoglobin (HH) and (ii) their ability to inhibit tryptophan (Trp) depletion and for the formation of specific protein carbonyls and pentosidine in the aforementioned proteins. Both proteins (20 mg mL(-1)) were allowed to react with postprandial plasmatic concentrations of the catechins (EC: 0.7 μM, EGC: 1.8 μM, and EGCG: 0.7 μM) under simulated hyperglycemic conditions (12 mM glucose/0.2 mM Fe(3+)/37 °C/10 days). The three catechins were able to inhibit Trp oxidation and protein carbonylation in both plasma proteins. Some anti-glycation properties were linked to their binding affinities. The molecular interactions reported in the present study may explain the alleged beneficial effects of tea catechins against the redox impairment linked to hyperglycemic conditions.

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“…The crude beer extract was treated with sulphite to dissociate covalent protein‐polyphenol bonds as has previously been demonstrated for β‐lactoglobulin covalently modified by 4‐methyl catechol ( 24 ) . The sulphite treatment significantly decreased the peak areas in chromatograms detected at 350 nm compared to untreated samples for beers subjected to medium and high levels of forced aging, which indicates that polyphenols were released from the protein by the sulphite treatment in the forced aged samples (Figure 2, lower panel).…”

Section: Resultsmentioning

confidence: 99%

“…Free, non‐covalently bound and covalently bound polyphenols were extracted from the crude beer extract by a combined method derived from Plundrich et al ( 27 ) and Jongberg et al ( 24 ) . An aliquot of 25 mg crude beer extract was mixed with 500 μL water for 10 min in an ultrasonic bath (20°C), 2 mL absolute methanol added and mixed again for 5 min in an ultrasonic bath (20°C).…”

Section: Methodsmentioning

confidence: 99%

“…The reactions of quinones with cysteine residues are kinetically preferred ( 22 ) , but in cysteine deficient proteins or peptides the selectivity between amino acid residues is poorly described ( 23 ) . We have previously shown that it is possible to dissociate covalent bonds between β‐lactoglobulin and 4‐methylcatechol by using reducing agents, such as sulphite, dithiothreitol, and tris(2‐carboxyethyl)phosphine, with sulphite being most effective ( 24 ) . Another recent study found that glutathione (GSH) is able to reverse the reaction by s‐transarylation reaction, transferring the quinone from the protein to GSH ( 23 ) .…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of protein-polyphenol interactions in beer during forced aging

2020

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Proteins and proteinaceous material were extracted by acetone precipitation of beer that had undergone forced aging through 0 (control), 5 (medium) or 10 (high) heat/chill cycles (60°C 48h/0°C 24h). Size exclusion chromatography analysis of the crude beer extract showed that forced ageing led to a significant increase in binding of phenolic compounds to Protein Z and especially to lipid transfer protein 1 (LTP1). Protein‐polyphenol conjugates were also present in high molecular weight (> 100 kDa) and low molecular weight fractions (< 5 kDa), but these conjugates were already present in the fresh beer and were not affected by the forced aging. Treatment of the crude beer extract with sulphite (2 M) dissociated the protein‐polyphenol bindings in LTP1 and Protein Z that had been generated during medium forced aging. Identification and quantification of the free, the non‐covalently, and the covalently bound phenolic compounds were performed by UHPLC after extraction by methanol, acetic acid, and sulphite, respectively. The amounts of vanillic acid and caffeic acid decreased in the free polyphenol fraction, indicating binding to proteins during forced aging. Epicatechin and quercetin‐3‐O‐glucoside were found to be non‐covalently bound during forced aging. Finally, gallic acid, epicatechin, protocatechuic acid, and astragalin were found to be covalently bound already in the fresh beer. © 2020 The Institute of Brewing & Distilling

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Dissociation and reduction of covalent β-lactoglobulin–quinone adducts by dithiothreitol, tris(2-carboxyethyl)phosphine, or sodium sulfite

Cited by 21 publications

References 39 publications

Quantitation of Protein Cysteine–Phenol Adducts in Minced Beef Containing 4-Methyl Catechol

Quantitation of Protein Cysteine–Phenol Adducts in Minced Beef Containing 4-Methyl Catechol

Redox chemistry of the molecular interactions between tea catechins and human serum proteins under simulated hyperglycemic conditions

Characterisation of protein-polyphenol interactions in beer during forced aging

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