In vitro peptidase activity of rat mucosa cell fractions against glutamine-containing dipeptides

Herzog, Birgit; Frey, Brigitte M.; Pogan, Karin; Stehle, Peter; Fürst, Peter

doi:10.1016/0955-2863(95)00195-6

Cited by 11 publications

(2 citation statements)

References 40 publications

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“…Studies were performed by the rapid fi ltration method as described previously [22,28] . Briefl y, 100 l vesicle suspension and 400 l buffer solution (150 mmol/l NaCl or KCl, 100 mmol/l Dmannitol, 10 mmol/l HEPES/Tris pH 7.5 or 10 mmol/l MES/TrisHCl pH 5.5) containing (+)-catechin or (-)-epicatechin were incubated for various time intervals (15 s-120 min).…”

Section: Transport Studiesmentioning

confidence: 99%

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Characteristics of (+)-Catechin and (–)-Epicatechin Transport across Pig Intestinal Brush Border Membranes

Starp

Alteheld

Stehle³

2006

Ann Nutr Metab

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Background/Aims: (+)-Catechin and (–)-epicatechin are considered as disease preventive flavan-3-ols of foods like fruits, beverages and chocolate. We investigated mechanisms and kinetics of (+)-catechin and (–)-epicatechin uptake employing a validated in vitro model with isolated pig brush border membrane vesicles. Methods: Vesicles were isolated from pig small intestine employing the divalent cation method. Characterization (marker enzymes, electron microscopy) confirmed their purity and function. Transport studies with (+)-catechin and (–)-epicatechin under predefined conditions [presence/absence of sodium, pH gradient, temperature (8–37°C), various initial substrate concentrations (2–20 mmol/l)] revealed a measurable transport (HPLC analyses) across the brush border membrane for both substrates. Re sults: Catechin transport was stimulated by an outwardly directed H⁺ gradient (pH_i 5.5/pH_o 7.5). The presence of an inwardly directed Na⁺ gradient did not result in a transient overshoot in (+)-catechin and (–)-epicatechin uptake. At 37°C, subtraction of diffusion from the total transport rate showed saturation kinetics. Conclusion: Our in vitro study indicate that both (+)-catechin and (–)-epicatechin are transported across the basolateral membrane using a dual transport system consisting of free diffusion (dominant at low concentrations) and carrier-mediated facilitated diffusion.

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Section: Transport Studiesmentioning

confidence: 99%

“…25-30 g wet weight) were placed in the standard buffer solution (20 mmol/ l KH 2 PO 4 , 5 mmol/l ethylene glycol-bis(2-aminoethyl ether)-N,N,N ,N -tetraacetic acid (EGTA), 140 mmol/l NaCl; pH 7.5). Brush border membranes were precipitated using the divalent cation (Mg 2+ ) method [21,22] . All steps were performed on ice.…”

Section: Preparation Of Bbmvmentioning

confidence: 99%