Sulfate moiety

In the simplest case a surfactant is composed of an organic hydrophobic part and a hydrophilic part (Fig. 3). In an alkyl sulfate the hydrophobic part is derived from a fatty alcohol and the sodium sulfate moiety as the hydrophilic counterpart. (Only small variations concerning the fatty chain are possible in this special kind of structure.)... 

After exerting their action in the organism, natural and synthetic hormones are catabolized in the liver by conjugation to glucuronide and/or sulfate moieties, forming more polar conjugated forms which are excreted via urine. This is the main route of hormone excretion in humans and pigs. A fraction of hormones is also excreted in a free form via feces in animals such as sheep and cattle this is the main route for hormone excretion (Table 3) [66, 67],... 

The synthesis of enantiomerically pure D-manno and L-gluco iminosugars 183 and 184, respectively, was achieved via reduction of an isoxazoline to an amine, which subsequently acts as a nucleophile in a spontaneous opening of the cyclic sulfate moiety <06JOC894>. 

Zwitterionic micelles of the sulfobetaine C16H33N+Me2(CH2)3SO 3 have effects very similar to those of cationic micelles (Table 7). This result is understandable if the substrate binds close to the quaternary ammonium center and the anionic sulfate moiety extends into the aqueous region. 

In writing balance equations for the partial equilibrium model, two quantities are absolutely conserved. These are the total number of sulfate moieties and the net charge in solution. The resulting equations are ... 

Indeed, it was shown that aposcopolamine was not formed by direct dehydration of scopolamine, but via the conjugate scopolamine O-sulfate generated by a sulfotransferase [127]. This explains the species differences observed, and indicates a mechanism of heterolytic C-0 bond cleavage made possible by the electron-withdrawing capacity of the sulfate moiety. The reaction is also facilitated by the acidity of the departing proton carried by the vicinal, stereogenic C-atom. This acidity also accounts for the facile base-catalyzed racemization of scopolamine and hyoscyamine [128]. 

This enzyme [EC 3.1.6.12] acts on 4-sulfate groups of the A-acetylgalactosamine 4-sulfate moieties in chondroitin sulfate and dermatan sulfate. 

This enzyme [EC 3.1.6.14] catalyzes the hydrolysis of the 6-sulfate moieties of the A-acetylglucosamine 6-sulfate subunits of heparan sulfate and keratan sulfate. It has been suggested that this enzyme might be identical to A-sulfoglucosamine-6-sulfatase. 

In contrast, the acid-catalyzed hydrolysis of alkyl selenates is A-2158. The actual species which undergoes decomposition to alcohol and sulfur trioxide is probably the zwitterion as in the case of phosphate monoester monoanions. Evidence for sulfur trioxide as the reactive initial product of the A-1 solvolysis is obtained from the product compositions arising with mixed alcohol-water solvents. The product distribution is identical to that found for sulfur trioxide solvolysis, with the latter exhibiting a three-fold selectivity for methanol. Although the above entropies of activation and solvent deuterium isotope effects do not distinguish between the conventional A-l mechanism and one involving rate-limiting proton transfer, a simple calculation, based on the pKa of the sulfate moiety and the fact that its deprotonation is diffusion controlled. 

Elemental analysis Quantitation by HPLC Analyses of the Sulfate Moiety Detection of [35s] sulfate Benzidine method Sodium rhodizinate method Estimation of lipid-bound sulfate... 

Comparison of the activity of sulfated homopolysaccharides such as dextran and cellulose esters with that of neutral homopolysaccharides and sulfated heteropolysaccharides such as heparin and heparan sulfuric acid half esters shows potent virucidal activity against human T-cell lymphotropic virus type III (HTLV-III) for the sulfated homopolysaccharides. In contrast, neutral homopolysaccharides have no effect and sulfated heteropolysaccharides exhibit only a little effect on HTLV-III activities. This suggests that the sulfate moiety and the type of polysaccharide are most important in inhibiting growth of HTLV-III [126]. 

Zhuo L, Salustri A, Kimata K. A physiological function of serum proteoglycan bikunin The chondroitin sulfate moiety plays a central role. Glycoconj J 2002 19 241-247. 

Movement of the sulfate moiety by one position towards the N-terminus ([TyrCSOgH), Phe , Nle ]LSK) led to a very significant 38% retention of parent peptide ([Nle ]LSK) activity. Movement of the sulfate group by two to five positions towards the N-terminus (represented by analogs [Tyr(S03H), Phe ,... 

The biochemical pathway of both assimilatory and dissimilatory sulfate reduction is illustrated in Figure 1. The details of the dissimilatory reduction pathway are useful for understanding the origin of bacterial stable isotopic fractionations. The overall pathways require the transfer of eight electrons, and proceed through a number of intermediate steps. The reduction of sulfate requires activation by ATP (adenosine triphosphate) to form adenosine phosphosulfate (APS). The enzyme ATP sulfurylase catalyzes this reaction. In dissimilatory reduction, the sulfate moiety of APS is reduced to sulfite (SO3 ) by the enzyme APS reductase, whereas in assimilatory reduction APS is further phosphorylated to phospho-adenosine phosphosulfate (PAPS) before reduction to the oxidation state of sulfite and sulfide. Although the reduction reactions occur in the cell s cytoplasm (i.e., the sulfate enters the cell), the electron transport chain for dissimilatory sulfate reduction occurs in proteins that are peiiplasmic (within the bacterial cell wall). The enzyme hydrogenase... 

In each case the sulfated metabolite undergoes active tubular. secretion by the OATS in proximal tubular cells and. hence, attains high levels in luminal fluid. The negatively charged sulfate moiety pruhably hinds to the Cr-binding. site on (he luminal membrane-bound INa /IK /2CI co-tran-sport. system of (hick ascending limb and macula densa cells. 

The long term objective of our work is to examine the applications of LC-MS in measuring human exposure to toxic substances. Specifically, we are investigating the direct measurement of polar and ionic metabolites of toxic compounds in the urine. Common mammalian metabolic routes include conjugation with glucuronide or sulfate moieties (9), and such conjugates are difficult to analyze by GC without extensive sample preparation (10, H). The model compounds chosen for this study and their typical parent compounds are shown in Table I. 

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