Bile salt hydrates

Crystal and molecular structures of 3 bile salt hydrates have been solved [7,51,53]. The crystallographic data (Table 2) show that all are monoclinic with 2 molecules in each unit cell. Whereas the anions are held together mainly by ion-ion and ion-dipole interactions between the counterions and the carboxylate and hydroxyl groups to which water molecules contribute, the crystal packing patterns are remarkably similar (Figs. 4 and 5). The crystal packing upon looking down the b 

Highly complex H-bond network all O atoms involved 

All O atoms involved in H bonding. H bonding to form zig-zag spirals parallel to b-axis. Further H bonding across ends of molecules to give sandwich sheet structure with non-polar exteriors. Na and HjO inside hydrophilic bilayers. Van der Waals contact of hydro-phobic bilayers. Counterion steroid-OH bonding 

Similar to Na cholate with the exception of no counterion-steroid OH bonding 

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The effect of low concentrations of urea (2M) on the large dihydroxy bile salt micelles is striking, while similar concentrations have no effect on the small trihydroxy or dihydroxy micelles. The effects of urea on micelle formation and aggregate size are undoubtedly complicated (10) and involve changes in solvent structure and thus hydrophobic bonding and hydration of polar groups. For large micelles of dihydroxy bile salt... 

Bile salts are substances derived from sterols, which make up a substantial part of the solid matter in bile and which play a central role in lipid absorption, by virtue of their surface-active properties. The structure and properties of these salts have been reviewed by Haslewood (305) and Heaton (316). Bile salts essentially have molecules of detergent type hydrocarbon, with a fat-dissolving part and a polar, water-attracting part. The fat-dissolving part consists of the bulk of the steroid nucleus. The hydroxyl groups are so distributed that hydration can readily take place the remainder of the molecule will dissolve the fatty phase. Emulsification of fat/water complexes can thus occur easily. The terms bile acid and bile salt are used somewhat interchangeably in the literature. 

Fig. 12. Partial phase diagrams for the dilute region of aqueous solutions of the disodium salts of sulfated monohydroxy bile salts glycolithocholate sulfate (GLCS at pH 10.0) and taurolithocholate sulfate (TLCS at pH 7.0, inset). The solid solubility curves and the interrupted CMC curves demarcate areas where crystals (and monomers), micelles (and monomers), and monomers alone are found. The critical micellar temperature (CMT) represents an equilibrium between micelles and hydrated crystals connected via the monomer concentration at the CMC. The Krafft point is a triple point and only represents the CMT at the CMC. (After ref. 6 with permission.)...

At low concentrations just above the CMC and at low ionic strengths ( < 0.2 M NaCl), nearly all simple bile salt micellar solutions contain spherical or nearly spherical micellar particles [5,6,12,146]. Intrinsic viscosity measurements [162,170-172] are in agreement with this and also indicate that the micelles are highly hydrated, cholates2 DC [162,172]. The maximum size of these globular micelles falls in the range Ry, = 10-16 A with h = 10-12 [146]. In the case of NaTC, the water of hydration amounts to about 30 moles H20/mole of monomer in the micelle [162]. By employing the translational mobility of H20, Lindman et al. [173]... 

Sodium taurocholate [2-(3a,7a,12a-trihydroxy-24-oxo-5-p-cholan-24-ylamino)ethanesulfonic acid sodium salt monohydrate] [145-42-6-, 312693-83-7 345909-26-4 (x H2O)] M 555.7 (monohydrate), m 168 dec (hydrate), [a] +23.9° (c 2.5, H2O), pK of acid is 1.4. The non-sulfated bile salt has been synthesised from... 

Taurocholate sodium Taurocholate sodium salt Taurocholic acid sodium salt Taurocholic acid sodium salt hydrate 2-[[(3a,5p,7a,12a)-3,7,12-Trihydroxy-24-oxocholan-24-yl] amino] ethanesulfonic acid sodium salt Definition Principal component of the bile of carniverous animals Empirical C2eH44NNa07S Properties Cryst sweet taste, bitter aftertaste very freely sol. in water, alcohol solvent action on cholesterol m.w. 537.69 dec. 230 C Toxicology May cause eye/skin/mucous membrane/upper respiratory tract irritation may be harmful by ing., inh., skin absorp. may cause eye effects, convulsions, respiratory changes TSCA listed... 

Bile contains three amphiphiles (cholesterol, lecithin and bile salts) assembled in mixed micelles. These greatly increase water-solubility of cholesterol (usually very low about 70-80 nM). If excess cholesterol is present, the solubilizing capacity of the micelles is exceeded and supersaturation reached nucleation of cholesterol molecules can occur with formation of cholesterol mono-hydrate crystals and stones[8]. Only ChM is found in gallstones and its dissolution rate is slower than anhydrous cholesterol[9]. 

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