Sulfate residues

In this step the recovered ether is collected in a dry atmosphere, and about 100 ml. of this ether is used in two portions to extract the sodium sulfate residue in order to transfer into the flask any small quantities of the aldehyde that may have been trapped by the drying agent. 

A cold mixture of sulfuric acid (98%, 4 g), and water (4 mL) was added to an amino-alcohol 25 (40 mmol) in water (2.4 mL) at 0-5°C. The mixture was heated to 120°C and then water was carefully distilled off in vacuo. The solid sulfate residue was treated with 6.2 M potassium hydroxide, and steam-distilled. The distillate was saturated with potassium hydroxide pellets and the upper organic layer, which separated, was fractionally distilled from potassium hydroxide through a short column to give a colorless oil aziridine 26 in 96% yield. 

On plant surfaces, as in soils, numerous studies have demonstrated that endosulfan is oxidized to endosulfan sulfate. Initial residues of endosulfan on treated vegetables generally range from 1 to 100 mg/kg. However, residue levels typically decrease to less than 20% of initial levels within 1 week after treatment (NRCC 1975). Residues of endosulfan isomers are generally negligible after 2-3 weeks the a-isomer is much less persistent than the P-isomer. In most plant residue studies, endosulfan sulfate residue levels tend to increase relative to the parent isomers and other metabolites and appear to be very persistent (Coleman and Dolinger 1982). 

Tolerances for endosulfan and endosulfan sulfate residues in or on raw agricultural commodities... 

Pesticide Tolerances in Food-endouslfan and endosulfan sulfate residue in or on dried tea... 

The molecules are helices having a twofold screw-axis, with an axial rise per disaccharide residue of 9.45 A (945 pm). The axes of the chains are parallel, and about equally spaced, but are not further organized into crystalline arrays. A hydrogen bond was proposed between the OH-3 group of the 2-acetamido-2-deoxy-D-glucose residues and 0-5 of the D-galactose 6-sulfate residues. 

The sialic acid residues are usually in a terminal position on the carbohydrate chain, whereas the ester sulfate residues are in a more internal position both contribute to give the molecule a net negative charge. The molecular weights of mucus glycoproteins range from 0.5 to 16 X 10 Da [4]. 

Mucin is negatively charged due to sialic acid and sulfate residues. 

This enzyme [EC 3.1.6.8], also known as arylsulfatase A, catalyzes the hydrolysis of a cerebroside 3-sulfate to produce a cerebroside and sulfate. The enzyme will also catalyze analogous reactions on the galactose 3-sulfate residues in a number of lipids as well as on ascorbate 2-sulfate and many phenol sulfates. 

This enzyme [EC 3.1.6.18], also known as glucuronate-2-sulfatase and chondro-2-sulfatase, catalyzes the hydrolysis of the 2-sulfate groups of the 2-O-sulfo-D-glucuro-nate residues of chondroitin sulfate, heparin, and hepari-tin sulfate. The enzyme does not act on iduronate 2-sulfate residues. 

The function of the sulfate residue in these polysaccharides is unknown but the suggestion has been made that just as starch is synthesised from D-glucose 1-phosphate by the action of phosphorylase, so the seaweed polysaccharides are formed from the appropriate sugar sulfate by reaction with a sulfatase. ... 

After the early discovery of a tyrosine 0-sulfate residue in bovine fibrinopeptide B, 15 this posttranslational modification which occurs ubiquitously in proteins was also detected in a series of biologically active peptides such as the neurohormones of the gastrin/cholecysto-kinin (CCK) family of peptides, phyllokinin, Leu-enkephalin, and the thrombin inhibitor hirudin listed in Table 1. 

Presently, FAB-MS spectra are routinely used to characterize synthetic tyrosine O-sulfate peptides.152,57,63-671 Since partial hydrolysis of the sulfate ester occurs in the gas phase, quantification of the tyrosine O-sulfate residue by mass spectrometry is not possible, but combined with one-peak assignment in HPLC, FAB-MS represents a powerful analytical tool. On the other hand, partial hydrolysis in the gas phase excludes the presence of sul-fonated species which should be perfectly stable. In early studies the presence of such species were excluded by quantitative recovery of tyrosine upon acid hydrolysis or upon hydrolysis with arylsulfatase.1361 Recently, even MALDI-TOF-MS spectra of CCK-peptides1441 and of conotoxins a-PnIA and a-PnlB 138 were reported which show that in the positive-ion mode the [M + H-S03]+ ions represent the base peaks, while in the negative-ion mode, [M-H]-ions consistently correspond to the base peaks. In the CCK peptides intramolecular salt bridging of the sulfate hemi-ester with proximal positive charges of arginine or lysine side chains was found to reduce the extent of hydrolysis in the gas phase significantly.144,1491... 

The 3-C-sulfated D-glucosaminyl-N-sulfate residue has been found only in active oligosaccharides. 

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