Acid hydrolysis taurine

Chemical hydrolysis or solvolysis is the only method available at present to remove sulfate groups from bile acids. It is known that some colonic bacteria possess a sulfatase which can utilize sulfated bile acids as substrate (H24), but this enzyme has not yet been purified. The position of the sulfate moiety in monosulfated bile acids is nearly always at C-3 and this group is easily removed by acid hydrolysis in ethereal solution after removal of glycine or taurine (VI). This method, however, does not remove sulfate groups from C-7 or C-12 (PI). For complete removal, other methods have been described, including solvolysis in acidified methanol-acetone for 18 hours at 37°C (P6), acidified ethyl acetate-ethanol for 16 hours at 39 C (A6), or acidified 2,2-dimethoxypropane for 12 hours at room temperature (C3). 

By thin-layer chromatography this lipid was isolated and named cerilipin. On hydrolysis, it gave ornithine and a sulphur-containing component identified as taurine. By alkaline transmethylation, cerilipin was deacylated and the resulting methyl ester was found to be identical with methyl 2-hydroxyhexadecanoate (with a small amount of methyl 2-hydroxylactobacillate). Acid hydrolysis of the deacylated lipid gave a fatty acid identified as 3-hydroxyhexadecanoic acid as well as ornithine and taurine, in the molecular ratio 1 1 1. Treatment of cerilipin with dinitrofluorobenzene gave -ornithine as the only DNP derivative. From these data, structure (14) was proposed for cerilipin 45). 

The two most important bile acids, cholic acid C24H40Os and desoxy-cholic acid C24H40O4, occur in ox bile in combination, partly with glycine and partly with taurine as glyco- and taurocholic and glyco- and tauro-desoxycholic acids. The linkage between the amino acids and the bile acids is of an amide nature. On hydrolysis the nitrogenous constituents are split off. 

For the quantitative estimation of bile acids in body fluids and tissues, consideration must be given as to whether (1) an extraction step is necessary to partially purify the bile acids prior to further analysis (2) hydrolysis is required to remove glycine and taurine or other conjugate moieties and (3) the method of analysis will be of the required sensitivity and provide infer-... 

To deconjugate bile acids for further analysis, particularly by gas-liquid chromatography, different methods are required for the hydrolysis of the peptide bonds in glycine and taurine conjugates than for hydrolysis of the ester sulfate and glucuronide bonds. Glycine and taurine may be removed by either alkaline or enzymatic hydrolysis (Rll). Alkaline hydrolysis is often... 

Unlike enzymatic or radioimmunoassay methods, GLC requires lengthy sample preparation before bile acid concentrations can be determined. In the case of serum, bile acids must be extracted (see Section 6.1) and hydrolysis carried out to remove glycine and taurine, and also sul te groups, if they are likely to be present (see Section 6.2). The free bile acids are then converted to volatile derivatives. 

A new, strongly acidic product, quinaldyl(carboxyl-14C)glycyltaurine (198), a sulphonic acid urinary metabolite, has been discovered163 and its chemical structure established by subcutaneous injections and oral administrations of quinaldic acid-carboxyl-14C to hungry cats. Hydrolysis of 198 demonstrated the presence of glycine, taurine, quinaldic acid and quinaldylglycine in the hydrolysate. 

The breakdown of protein and amino acids in the intestinal tract and their enzymatic hydrolysis in cells releases sulfur from sulfur-containing proteins. The biological importance of sulfur partly involves the amino acids methionine, cysteine and taurine, and other metabolites such as glutathione and N-acetyl-methionine. Hence, sulfur plays biochemical and physiological... 

Norman (3) demonstrated that the types of bile acids found in normal rat bile were not the same as those which were excreted in the feces. However, when the rats were fed high levels of antibiotics, the fecal bile acids were excreted essentially unchanged from the biliary bile acids (4). The intestinal bacteria were responsible for the hydrolysis of the biliary taurine-conjugated bile acids to the free bile acids found in the feces. Norman also showed that the dehydroxylation of cholic acid to deoxycholic acid could be prevented by Inhibiting the intestinal bacteria. The total amount of fecal bile acid excreted by conventional chicks has been found to be significantly lowered (5) by incorporation of an antibiotic into the diet. 

The starting material for the synthesis of Taurolin is 2-aminoethanolsulphonic acid (Taurin) which by the addition of 2 m NH3 and 3 M CH2O in a condensation reaction is converted to Taurolin. The spectrum of effectiveness corresponds to that of formaldehyde, however, according to findings of Myers et al (1980) and All wood Myers (1981) the activity of Taurolin is considerably greater than that of formaldehyde apparently the 4-hydroxymethyl-1,1-dioxoperhydro-1,2,4-thiadiazine which is released in the first step on hydrolysis of Taurolin plays an important role in the mechanism of Taurolin s antimicrobial activity. 

The rate of hydrolysis may vary with the bile acid structure. The hindered nature of the peptide bond in the taurine-conjugated 3 ,7a, l2a-trihydroxy-5 3-cholestanoic acid may explain why this conjugate is more resistant to saponification than C24 acids (59). 

For the identification of bile acids in bile from man and different animals, Kuksis (13) and co-workers have used ion-exchange chromatography for the separation of glycine- and taurine-conjugated bile acids. After alkaline hydrolysis, extraction, and methylation, the bile acids were analyzed on SE-30 and QF-1 columns. Tentative identifications were supported by additional gas-liquid chromatographic analysis of methyl ester acetates and methyl ester trifluoroacetates. The latter derivatives were also analyzed on OV-17 columns (117). 

Chemically, the bile acids are hydroxylated derivatives of cholanic acid, a tetracyclic steroid acid of 24 carbon atoms. The acids occur in nature largely as the water-soluble sodium salts of peptide conjugates of glycine and taurine. The free acids are liberated by saponification or specific enzyme hydrolysis. The chemistry of the bile acids has been reviewed in Chapter 1 of this volume (1). In view of their highly polar nature, special attention is called to the recent discovery of the cholic acid conjugates of ornithine (2, 3) and the 3a-sulfate esters of glycolithocholic and taurolithocholic acids (4). 

This hydroxamation reaction occurs under alkaline conditions (131-133). Carboxyl groups can be produced because of the hydrolysis of the amide (131, 132). Acrylamide polymers can also be reacted with primary amines such as 2-aminoethanesulfonic acid (taurine) [107-35-7] at high temperature and acid pH to yield N-substituted copolymers containing sulfoethyl groups (134). 

Amino acids are the building blocks of proteins upon hydrolysis of plant and animal tissues, the 20 protein amino acids mentioned in Section I will usually be obtained. Amino acids are also found free (referred to as free-pool amino acids) in animal and plant tissues and in the blood of vertebrates and invertebrates. Qualitative and quantitative differences may exist in the free-pool amino acids of different species, and the significance of such variations is obscure. However, amino acid variations in species may be important in studies on the chemotaxon-omy of organisms (Gilbertson and Schmid, 1975). By way of an example of differences in free-pool amino acids in related organisms, the most abundant free-pool amino acids in the rat tapeworm, Hymenolepis diminuta, are alanine and glutamic acid. By contrast, the most abundant free-pool amino acids in tapeworms of elasmobranchs (sharks and rays) are glycine and taurine (von Brand, 1973). It should be remembered, however, that a variety of analytical techniques are used to determine free-pool amino acids, and some of the interspecific variations reported in the literature may actually reflect differences in analytical procedures used. 

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