Bile acid conjugates function

The taurine residue can also be found as an amide derivative of the 26-carboxylic acid function in the 3p,5a,6p,15a-polyhydroxylated steroids 328 and 329, which were obtained from the starfish Myxoderma platyacanthum [245]. The structures of both compounds were determined from spectral data and chemical correlations. The bile of the sunfish Mola mola has been shown to contain a new bile acid conjugated with taurine (330) together with sodium taurocholate. Compound 330 was identified as sodium 2-[3a,7a, 11 a-trihydroxy-24-oxo-5P-cholan-24-yl]amino]ethane-sulfonate on the basis of its physicochemical data and chemical transformations [246]. 

Cysteine Precursor of taurine (used in bile acid conjugation and for other functions) reducing... 

Bile acid conjugation has been suggested to be a function of the availability of taurine and glycine in the liver (Hardison 1978). In the only period of TPN in which bile salts were measured, i.e. 21-35... 

It is bejmnd the scope of this pr ntation to consider the physiological functions of bile acid conjugates in detail. However, to place the conjugates in their proper biological perspective, it seen neceasarj to discuss some points. 

B. Function os Bile Acid Conjug. tes in the Small Intestine... 

The functions of bile acid conjugates within the small intestine during lipid absorption have been studied extensively (Senior, 1964 Hofmann and Small, 1967). The bile salts are utilized to emulsify lipids, to facilitate digestion of lipids, and to maintain the products of digestion in micellar suspension. Hence, they have a central role in the absorption of fat and lipid-soluble substances such as vitamin D, vitamin K, and carotene. 

C. Function of Bile Acid Conjugates in the Portal and Hepatic Part of the Entbrohepatic Circulation... 

As already pointed out, cysteine may be metabolized to pyruvate, or it can be oxidized to cystine. It can also be converted to taurine, NH3+-CH2-CH2-S03. Taurine is obtained by oxidizing the -SH group of cysteine and losing the carboxyl group of decarboxylation. Taurine is quite abundant in most tissues and is said to be the most abundant "amino acid" of the human organism. One of its functions is to conjugate primary bile acids (Chapter 19). 

Taurine was discovered in 1827 in ox hUe, where it is conjugated with the bile acids. It was later shown to be a major excretory product of the sulfur amino acids methionine and cysteine. Until about 1976, it was assumed that it was a metabolic end-product whose only function was the conjugation of bile acids. In the rat, taurine synthesis accounts for 70% to 85% of total cysteine catabolism. 

Chromatography.—Considerable attention is being paid to chromatographic methods for the separation and recognition of bile acids and their derivatives. The analysis (g.l.c.) of mixtures of bile acids and their conjugates is reported to be simplified by direct conversion into heptafluorobutyrate derivatives, which occurs with simultaneous deconjugation.The carboxyl function is apparently converted into its volatile mixed cholanyl-heptafluorobutyryl anhydride. Ethyl-dimethylsilyl ethers of bile acid ethyl esters are also reported to be suitable for... 

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