Taurine conjugates

James MO, JR Bend (1976) Taurine conjugation of 2,4-dichlorophenoxyacetic acid and phenylacetic acid in two marine species. Xenobiotica 6 393-398. 

The separation of the individual glycine and taurine conjugates by successive 74... 

Ohshima M, Yoshida S, Saito S, Mikami N, Matsuo M (1992) Taurine conjugation of the ester metabolite of prallethrin in bluegill sunfish, Lepomis macrochirus. J Pestic Sci... 

Some further generalities can be made from data in this table. Except for octane with its known CNS depressant actions, no other compound appeared in significant quantities in the brain. The herbicides were the only compounds which occurred in significant concentrations in the bile and this has been shown (32) to be mainly metabolites, i.e., the taurine conjugates of 2,4-D and 2,4,5-T. Also the kidney and urine samples contained large concentrations of these same herbicides as did those from fish treated with octane or DEHP. Presumably these latter values are at least in part metabolities. Due to its large mass (ca. 

Table 1.1 lists some of the characteristics of the more common bile acids, which are divided into 3 main classes free bile acids, glycine and taurine conjugates. 

The first studies of specificity were carried out using cholate, the glycine and taurine conjugates and taurine conjugates of the dihydroxy bile acids cheno-deoxycholate and ursodeoxycholate. Kramer and colleagues prepared plasma membrane vesicles from rat liver and compared bile-acid transport with values from CHO cells stably expressing NTCP. This work established that transport by the liver enzyme was maximal when 2 hydroxyls were present,... 

FI GURE 4.3 Structures of allocholic acid (petromyzonol sulfate is identical apart from replacement of the carboxyl group with sulfate), taurine-conjugated bile acid, and geosmin. 

Taurine-conjugated fatty acids) Fig. 4. Known endocannabinoids congeners. 

Free bile acids Glycine conjugates Taurine conjugates... 

Stock solutions of free, and glycine- and taurine-conjugated BA in methanol. 

Human serum sample (0.5 ml), diluted with 2.5 ml of 0.1 N NaOH is incubated at 65°C for 15 min. The free, and glycine- and taurine-conjugated fractions are isolated by means of solid-phase extraction, using BE C18 and BE SAX cartridges in succession [23]. The taurine fraction is enzymatically hydrolysed according to a previously described method [24]. The final residue is treated with 1 ml volume of 0.01% (w/v) KOH methanolic solution (methanokwater 1 9, v/v) at 40°C by ultrasonication for 3 min. Then, 0.2 ml of the obtained suspension is derivatised as described below. BA content is determined in each sample by comparison with an appropriate standard solution. 

The chromatogram of free BA standard mixture is reported in Fig. 5.4.7. The Br-AMN degradation products are eluted at lower retention times than derivatised BA, close to the solvent front, so they do not impair BA separation. Free BA fraction also encloses taurine conjugates, previously enzymatically hydrolysed. The separation of glycine conjugated BA is illustrated in Fig. 5.4.8. In both chromatograms, the peaks of BA naphthacyl esters are fully resolved and separated from the reagent peaks. 

Used BA standards, CA, CDCA, DCA, UDCA, LCA, and their glycine- and taurine-conjugated forms are dissolved in methanol at a concentration of 1 mg/ml. 

This method allows a quantitative analysis of BAs present in biological fluids (free, and glycine- and taurine-conjugated forms) in a single chromatographic run, performed with an HPLC mass spectrometric system equipped with an electrospray interface [33]. 

Table 5.4.14 Mobile phase gradient composition used for simultaneous separation of free, and glycine- and taurine-conjugated BA within a single run (adapted from [33])...

Figure 5.4.14 illustrates a MALDI spectrum of a plasma sample spiked with glycine conjugate (47.62 mg/ml) and taurine conjugate (3.175 mg/ml). 

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