Desulfation

Examination of early -n.m.r. spectra of heparin and of chemically modified heparins121 prompted a reinvestigation of N,0-desulfated, carboxyl-reduced heparin, leading to the isolation of substantial amounts of L-iditol pentaacetate.121,122 In addition, improved conditions for the acid hydrolysis of heparin and carboxyl-reduced heparin gave increased recoveries of L-iduronic acid and 1,6-anhydro-L-idose, respectively.123 These findings confirmed the L-enantiomeric designation of the iduronic acid, and established that it is the main uronic acid in heparin. 

Whereas the configuration at C-l of the amino sugar units in heparin was established as a-D by early studies, especially the structural characterization129 of crystalline disaccharide 9, the configuration of the D-glucuronic acid has been the subject of controversy. It was originally presumed to be a-D, on the basis of the structure proposed for a disaccharide obtained, in addition to 9, from desulfated, carboxyl-reduced heparin.129... 

Residues of non-N-substituted 2-amino-2-deoxy-D-glucose constitute only a tiny fraction (if any) of the total amino sugar of heparin and heparan sulfate. Although free amino groups are produced in the biosynthesis20,23 of heparin (between stages 1 and 2, see Scheme 1), the small proportions occasionally found in heparin and heparan sulfate preparations are most probably the result of some N-desulfation during extraction, or purification, or both. 

Acid cleavage of reduced oxyheparins occurs at pH 1-3 during155 15 min at 100°, or151 with 5 mMH2S04 during 3 h at 60°. Some desulfation of fragments was reported for Smith-degraded heparan sulfate.151 Also, elimination at pH 12 for 30 min at 20° may cause some loss of sulfate.151... 

Sulfoamino groups may be restored on N-desulfated heparins by treat-... 

The nondestructive introduction of a fluorescent label would provide the molecule with a nonradioactive fluorophore, yet would preserve the option for direct radiolabelling of the fluorescent moiety with 125Iodine. This approach was pioneered by Nagasawa et al. (5) who reacted native or /V-desulfated heparins with a fluorescein isothiocyanate (FITC). The resulting degree of labelling was low... 

Fortunately, desulfation sequences are not frequent and are spaced out by several thousands of kilometers. Desulfation process requires, at the same moment ... 

Dermatan sulfate, also termed chondroitin sulfate B, a related glycosaminoglycan constituent of connective tissue, was known to be composed of galactosamine and a uronic acid, originally believed to be glucuronic acid but then claimed to be iduronic acid based largely on color reactions and paper chromatography. However, the d or L-enantiomer status of the latter monosaccharide was not clear. Jeanloz and Stoffyn unequivocally characterized the monosaccharide as L-iduronic acid by consecutive desulfation, reduction, and hydrolysis of the polysaccharide, followed by isolation of the crystalline 2,3,4-tri-0-acetyl-l,6-anhydro-/ -L-idopyranose, which was shown to be identical to an authentic specimen synthesized from 1,2-0-isopropylidene-/ -L-idofuranose.34... 

DEsulf A process for removing hydrogen sulfide from coke-oven gas by scrubbing with aqueous ammonia. Developed by Didier Engineering. 

Red algae can produce many different polysaccharide structures, and four of these were examined, and differentiated, by means of the C-l region of their 13C-n.m.r. spectra.157 These were agar (24), K-carra-geenan (25 R = S03-Na+), partially desulfated K-carrageenan (25 R = S03-Na+ or H+), and i-carrageenan (26), three of which have predomi-... 

Fig. 27.—C-l Portions of, 3C-N.m.r. Spectra of Agar (A 24 from Ahneltia plicata), K-Carrageenan (B 25, R = S03 Na+ from Eucheuma striatum), Partially Desulfated k-Carrageenan (C 25, R = S03 Na+ or H), and t-Carrageenan (D 26, R = R = S03 Na+ from Eucheuma spinosum). (Samples were examined as sodium salts in DzO at 90° chemical shifts, 8C, are values relative to external tetramethylsilane.)...

Saiki, K., Yoshida, N., Silver, M.M. Kumagai, I. (1995) New desulfation system for chlor-alkali plant. In Modern Chlor-alkali Technology (ed. R.W. Curry), Vol. 6, pp. 82-88. ICI Chemicals and Polymers Ltd., Runcorn, UK. 

Although UGTs catalyze only glucuronic acid conjugation, CYPs catalyze a variety of oxidative reactions. Oxidative biotransformations include aromatic and side chain hydroxylation, N-, O-, S-dealkylation, N-oxidation, sulfoxidation, N-hydroxylation, deamination, dehalogenation and desulfation. The majority of these reactions require the formation of radical species this is usually the rate-determining step for the reactivity process [28]. Hence, reactivity contributions are computed for CYPs, but a different computation is performed with the UGT enzyme (as described in Section 12.4.2). 

Terao, K., et al., Histopathological studies on experimental marine toxin poisoning - 5. The effects in mice of yessotoxin isolated from Patinopecten yessoensis and of a desulfated derivative, Toxicon, 28, 9, 1095, 1990. 

The biologically inactive estrone sulfate (EIS) and dehydro-epiandrosterone-sulfate (DHEAS) are the most abundant circulating estrogenic precursors in the plasma of post-menopausal women [103]. Desulfation of inactive steroid-3-0-sulfates by estrone-sulfatase (STS) plays a key role in the regulation of levels of receptor-active estrogenic steroids (estradiol and androstenediol) in breast cancer cells (Fig. 9). There is strong evidence suggesting that estrone sulfatase (STS) and DHEA-sulfatase are the same enzyme [103]. 

Heparin s action is terminated by uptake and metabolism by the reticuloendothelial system and liver and by renal excretion of the unchanged drug and its de-polymerized and desulfated metabolite. The relative proportion of administered drug that is excreted as unchanged heparin increases as the dose increases. Renal insufficiency reduces the rate of heparin clearance from the blood. 

Figure 4 Desulfation Rates of Leucosulfakinin-II (A) and CCK-12 (B) in Acidic Media at 4 °Cl la...

For the analytical characterization of sulfated tyrosine peptides, spectroscopic methods as well as amino acid analysis and, more recently, mass spectrometry are employed. In Table 2 the spectroscopic data of tyrosine 0-sulfate are compared to those of the related sulfonic acid derivatives as possible byproducts in the chemical sulfation of the tyrosine or tyrosine peptides.[361 In the course of the synthesis of tyrosine 0-sulfate peptides and, particularly in the final deprotection step, desulfation may occur which limits the characterization of the final compounds in terms of quantitative identification of the tyrosine 0-sulfate. This is achieved by amino acid analyses of basic hydrolysates of the sulfated tyrosine peptides or preferably by analyses of the enzymatic hydrolysates with aminopeptidase M or leucine-aminopeptidase. 

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