Taurocholate, binding

Results of sodium taurocholate binding from two experiments employing different combinations of sodium taurocholate and fibrous material was given in Table IV. There was a significant difference among tobacco types but not within a given type. 

Does Citrus Pectin Bind Bile Salts A possible mechanism by which dietary pectin may cause lowering of cholesterol levels in rats has been reported (1 9). In these in vitro studies, pectin was found to inhibit the transport of taurocholic acid from everted sacs of rat intestine. The absorption of labelled cholesterol was depressed by the addition of 5% pectin to the diet as evidenced by increased excretion of labelled cholesterol and diminished cholesterol deposition in the liver. It was concluded from these studies that pectin lowers cholesterol levels in cholesterol-fed rats primarily by binding bile salts and, consequently, by impairing cholesterol absorption. Results similar to those obtained with dietary pectin and described have also been reported for other non-nutritive substances such as guar gum, psyllium seed colloid and seruglucan (20). 

Different filter supports have been tested nitrocellulose (NC), polycarbonate (PC), aluminium oxide (AO), polyethylenterephtalate (PET). NC filters have shown reduced non-specific binding compared to AO filters but seem to interact with marker PEG and steroids (Nicklin et al. 1992). AO filters displayed only half of permeability of PC for taurocholic acid. Reproducibility of binding and transport experiments was improved with PC filters (Hidalgo et al. 1989). Pore size is an important factor which needs to be considered and tested CACO-2 cells migrate through pores > 1 xm (Tucker et al. 1992 Hilgers et al. 1990). PET filters are translucent and allow microscopic observation as well as staining procedures. 

Triton X-100 solution are added to culture dishes to lyse cells by shaking the dish on a shaker for 20 min at room temperature. An aliquot (1 ml) of lysate is analysed by liquid scintillation spectrometry. All values for taurocholate uptake into cell monolayers are corrected for non-specific binding to the collagen... 

Donor wells pH 6 and pH 7 (ionization-maintained sink), 5-10 mm bile acid, such as taurocholic acid or glycocholic acid to solubilize lipophilic molecules (binding-... 

Glyceryl monooleate + sodium taurocholate Linoleic acid + HCO60 Calcium binding agents EDTA (ethylenediaminetetraacetic acid) Phenothiazines Chlorpromazine Liposomes Azone... 

Since plasma lipoprotein cholesterol must be the major substrate for bile acid biosynthesis under conditions when the rate of hepatic synthesis of cholesterol is low, regulation of the uptake of lipoprotein cholesterol by the hepatocytes should be of importance not only for the rate of cholesterol synthesis but also for the activity of cholesterol 7a-hydroxylase. It should be mentioned that bile acids are included among the different factors known to be able to modulate the receptor-mediated uptake of cholesterol by the apo-B, E or LDL receptor. The apo-B, E receptor can thus be induced to high levels by treatment with a bile acid sequestrant ]259]. Angelin et al. have shown that preparation of a bile fistula in adult dogs markedly induced the expression of the apo-B, E receptor and that the binding of this receptor could be almost totally abolished by reinfusion of taurocholate [260]. 

Binding of sodium taurocholate by the fiber was the method of Krltchevsky and Story (15). A 50 or 100 mg sample of fiber... 

Table IV. Binding In Vitro of Sodium Taurocholate to Tobacco and Alfalfa Fibrous Residues and Wheat Bran...

Consistent with the notion that this is an active process was the observation that metabolic inhibitors compromised transport (Fig. 1). The mechanism of coupling taurocholate translocation to metabohc energy is poorly understood. Some evidence is consistent with recent hypotheses developed for the transport of other organic compounds. An example of these hypotheses was presented by Curran et al. (18) and involves the interaction of sodium ions and amino acid transport. It is postulated that the uphill transport of amino acids into the mucosal cell depends on the maintenance of high extracellular and low intracellular sodium ion concentrations. The high extracellular sodium concentration, by enhancing sodium binding to a... 

ABC, ATP-binding cassette transporter superfamily ASBT, apical sodium-dependent bile salt transporter BCRP, breast cancer resistance protein BSEP, bile salt export pump MDRl, multidrug resistance MRR multidrug resistance-related protein NTCP, sodium taurocholate cotransporting polypeptide OAT, organic anion transporter OCT, organic cation transporter SLC, solute-linked carrier transporter family SLCO, solute-linked carrier organic anion transporter family. 

The cellular uptake process for taurocholate was found to be linear for at least the first four min for all substrate concentrations examined. The initial rate of uptake (Vq) was determined from linear regression analysis of the increase in taurocholate concentrations in the cell pellet with time (1-4 min). The regression correlation coefficient in all cases was greater than 0.95. Extrapolation of the Vq line to zero time yielded a positive intercept indicative of nonsaturable nonspecific binding such as adherence to the outer cell membrane. The derived values for Vq were combined within each age-group and substrate concentration. These values were then analyzed according to Michaelis-Menten kinetics using Lineweaver-Burk or Eadie-Hofstee plots to obtain and V gx (Dixon and Webb, 1964). 

Muzzarelli, RAA Orlandini, F Boselli, E Frega, NG Tosi, G Muzzarelli, C. Chitosan taurocholate capacity to bind lipids and to undergo enzymatic hydrolysis An in vitro model. Carbohydrate Polymers, 66 (3), 2006, 363-371. 

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