Physico-chemical behavior of bile salts

O’Connor, Charmian J.; Wallace, Robert G.

doi:10.1016/0001-8686(85)80002-6

Cited by 126 publications

(143 citation statements)

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“…Synthetic human bile (SHB) is a mixture of six purified conjugated bile acids added to LB medium at physiologically relevant concentrations to mimic the human small intestine (25,26,41,42). All bile acids were purchased from Sigma.…”

Section: Methodsmentioning

confidence: 99%

“…BV was added as a supplement to the medium at 0.4% (wt/vol), a concentration which is physiologically relevant to that found in the small intestine (27,54). SHB is a mixture of six purified bile acids that replicate the physiological concentrations of bile acids found in the human small intestine (25,26,41,42). To our surprise, growth in both BV-and SHBcontaining media significantly increased the intracellular concentration of c-di-GMP, 4.4-and 3.6-fold, respectively ( Fig.…”

Section: Bile Increases the Intracellular Concentration Of C-di-gmp Imentioning

confidence: 99%

“…The composition of secreted bile is heterogeneous and includes inorganic salts, cholesterol, phospholipids, pigments, and bile acids (25). Bile acids are derived from cholesterol in the liver and are processed by hepatic cells to produce a mixture dominated by taurine and glycine conjugates (25,26). Bile acids have detergent properties that enable the interaction between bile and digestive lipids.…”

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confidence: 99%

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Bile Acids and Bicarbonate Inversely Regulate Intracellular Cyclic di-GMP in Vibrio cholerae

Koestler

Waters

2014

Infect Immun

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Vibrio cholerae is a Gram-negative bacterium that persists in aquatic reservoirs and causes the diarrheal disease cholera upon entry into a human host. V. cholerae employs the second messenger molecule 3=,5=-cyclic diguanylic acid (c-di-GMP) to transition between these two distinct lifestyles. c-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and hydrolyzed by phosphodiesterase (PDE) enzymes. Bacteria typically encode many different DGCs and PDEs within their genomes. Presumably, each enzyme senses and responds to cognate environmental cues by alteration of enzymatic activity. c-di-GMP represses the expression of virulence factors in V. cholerae, and it is predicted that the intracellular concentration of c-di-GMP is low during infection. Contrary to this model, we found that bile acids, a prevalent constituent of the human proximal small intestine, increase intracellular c-di-GMP in V. cholerae. We identified four c-di-GMP turnover enzymes that contribute to increased intracellular c-di-GMP in the presence of bile acids, and deletion of these enzymes eliminates the bile induction of c-di-GMP and biofilm formation. Furthermore, this bile-mediated increase in c-di-GMP is quenched by bicarbonate, the intestinal pH buffer secreted by intestinal epithelial cells. Our results lead us to propose that V. cholerae senses distinct microenvironments within the small intestine using bile and bicarbonate as chemical cues and responds by modulating the intracellular concentration of c-di-GMP.

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Section: Methodsmentioning

confidence: 99%

Section: Bile Increases the Intracellular Concentration Of C-di-gmp Imentioning

confidence: 99%

mentioning

confidence: 99%

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Bile Acids and Bicarbonate Inversely Regulate Intracellular Cyclic di-GMP in Vibrio cholerae

Koestler

Waters

2014

Infect Immun

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“…Although it has been described that the pH of the duodenum may vary within the range 5-7 [27][28][29], the most accurate range seems to be 6-6.5 [30][31][32][33][34]. Therefore, the pH of the digests was adjusted to 6.5 and the following were added (a) a bile salt mixture containing equimolar quantities (0.125 m) of sodium taurocholate (Sigma) and glycodeoxycholic acid (Calbiochem, La Jolla, CA, USA), …”

Section: In Vitro Duodenal Digestion (Phase 2)mentioning

confidence: 99%

Stability of the major allergen Brazil nut 2S albumin (Ber e 1) to physiologically relevant in vitro gastrointestinal digestion

et al. 2004

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2S storage albumins occur in a diverse range of plant seeds, are members of the prolamin superfamily [1] and constitute one of the most important major plant food allergens that sensitize via the gastrointestinal (GI) tract [2]. Among the tree nuts, Brazil nut is frequently associated with immunoglobulin E (IgE)-mediated food allergy [3], the 2S albumin, known as Ber e 1, being the major allergen [4]. 2S albumins are considered to be structurally homologous, typically heterodimeric (small and large subunits of 4000 and 9000 M r , respectively) globular proteins. They have a conserved skeleton of cysteine residues (typical of members of the prolamin superfamily), which form four intermolecular disulphide bonds that hold the two subunits together and contribute to their stability and compactness [5]. This rigid The major 2S albumin allergen from Brazil nuts, Ber e 1, was subjected to gastrointestinal digestion using a physiologically relevant in vitro model system either before or after heating (100°C for 20 min). Whilst the albumin was cleaved into peptides, these were held together in a much larger structure even when digested by using a simulated phase 1 (gastric) followed by a phase 2 (duodenal) digestion system. Neither prior heating of Ber e 1 nor the presence of the physiological surfactant phosphatidylcholine affected the pattern of proteolysis. After 2 h of gastric digestion, 25% of the allergen remained intact, 50% corresponded to a large fragment of M r 6400, and the remainder comprised smaller peptides. During duodenal digestion, residual intact 2S albumin disappeared quickly, but a modified form of the 'large fragment' remained, even after 2 h of digestion, with a mass of 5000 Da. The 'large fragment' comprised several smaller peptides that were identified, by using different MS techniques, as deriving from the large subunit. In particular, sequences corresponding to the hypervariable region (Q37-M47) and to another peptide (P42-P69), spanning the main immunoglobulin E epitope region of 2S albumin allergens, were found to be largely intact following phase 1 (gastric) digestion. They also contained previously identified putative T-cell epitopes. These findings indicate that the characteristic conserved skeleton of cysteine residues of 2S albumin family and, particularly, the intrachain disulphide bond pattern of the large subunit, play a critical role in holding the core protein structure together even after extensive proteolysis, and the resulting structures still contain potentially active B-and T-cell epitopes.Abbreviations GI, gastrointestinal; IgE, immunoglobulin E; SGF, simulated gastric fluid; PtdCho, egg l-phosphatidylcholine.

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“…It has been shown that the CMC values determined by the same technique in different laboratories are very dispersed, especially for the trihydroxy bile salts [2,[6][7][8][9]. Furthermore, it has been demonstrated that the CMC measurements made in one laboratory using different techniques are also not in good agreement [2,[10][11][12].…”

Section: Introductionmentioning

confidence: 99%

The CMC-like behaviour of bile salts as probed by photoexcited Rose Bengal

Seret

Bahri

2009

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The onset of the aggregation process in aqueous bile salt (BS) solutions remains a debated question. This study aimed at investigating this point through the detection of BS monomers and small aggregates using the dye Rose Bengal. Results showed that a few small BS aggregates led to a red shift of the absorption spectrum, while the BS monomer reacted with the photo-induced semi-oxidized dye and decreased its decay rate constant. The dye was dissolved in aqueous solution (10 mmol dm -3 NaOH) of sodium cholate (NaC), deoxycholate (NaDC), chenodoxycholate (NaCDC), dehydrocholate (NaDHC), glycocholate (NaGC) glycodeoxycholate (NaGDC), taurocholate (NaTC), taurodeoxycholate (NaTDC) and the zwitterionic analogue of sodium cholate called CHAPS. BS aggregates were detected at concentrations well below the concentration above which any added bile salt molecules

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Physico-chemical behavior of bile salts

Cited by 126 publications

References 245 publications

Bile Acids and Bicarbonate Inversely Regulate Intracellular Cyclic di-GMP in Vibrio cholerae

Bile Acids and Bicarbonate Inversely Regulate Intracellular Cyclic di-GMP in Vibrio cholerae

Stability of the major allergen Brazil nut 2S albumin (Ber e 1) to physiologically relevant in vitro gastrointestinal digestion

The CMC-like behaviour of bile salts as probed by photoexcited Rose Bengal

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