Sulfate synthetic studies

Since the publication in 1986 (13,16) of the gastrin/cholecystokinin-like leucosulfakinins (LSK s), several additional insect sulfakinins have been structurally characterized (Table II). The structures of the Drosophila sulfakinins (DSK s) were deduced from a gene sequence which was isolated from Drosophila genomic DNA and head cDNA libraries (17). Although expression of the DSK s remains to be demonstrated, sulfated synthetic replicas are biologically active on the isolated cockroach hindgut (Holman, unpublished observation) as predicted by a study (18) which demonstrated that the hexamer, Tyr(S03)-Gly-His-Met-Arg-Phe-NH2, was the "core structure required for myotropic activity. 

Most studies of micellar systems have been carried out on synthetic surfactants where the polar or ionic head group may be cationic, e.g. an ammonium or pyridinium ion, anionic, e.g. a carboxylate, sulfate or sulfonate ion, non-ionic, e.g. hydroxy-compound, or zwitterionic, e.g. an amine oxide or a carboxylate or sulfonate betaine. Surfactants are often given trivial or trade names, and abbreviations based on either trivial or systematic names are freely used (Fendler and Fendler, 1975). Many commercial surfactants are mixtures so that purity can be a major problem. In addition, some surfactants, e.g. monoalkyl sulfates, decompose slowly in aqueous solution. Some examples of surfactants are given in Table 1, together with values of the critical micelle concentration, cmc. This is the surfactant concentration at the onset of micellization (Mukerjee and Mysels, 1970) and can therefore be taken to be the maximum concentration of monomeric surfactant in a solution (Menger and Portnoy, 1967). Its value is related to the change of free energy on micellization (Fendler and Fendler, 1975 Lindman and Wennerstrom, 1980). 

In STP effluents, total extractable estrogens and conjugates have been detected at levels up to 1 /jg/L [9,11,26]. Despite the wide variability in terms of removal efficiency reported for different WWTPs, a general trend has been observed with respect to the identity of the compounds most frequently detected in WWTP effluents. Thus, of the various compounds most commonly monitored - namely, estradiol, its metabolites estriol and estrone, and the synthetic estrogen ethynylestradiol - estrone is the most ubiquitous both in WWTP effluents and in environmental waters in general, while the most potent estrogens estradiol and ethynylestradiol have only occasionally been detected [26,40-42]. As for the conjugates, the very few studies that have attempted their determination pointed out estrone sulfates as the most abundant, while glu-curonides are most often found below the limit of detection [26,36,38,39]. 

Interactions can also be studied at the surface of a coated capillary wall. One binding partner is first immobilized on the capillary wall. As a result of the affinity of the second binding partner, the analyte will be delayed, compared with migration times observed in an untreated capillary. Based on this approach, modified capillaries have been prepared and used successfully to study polysaccharide-protein interactions as well as affinity separations. Coating of the capillary wall with heparin and heparan sulfate has been used to determine the affinity of these polysaccharides for synthetic heparin-binding peptides different only in the stereochemistry of a single... 

Luminescence of in synthetic alkaline earth sulfates is well known (Folk-erts et al. 1995). In this study, CaS04 Pb shows an emission band with a maximum at 235 nm at 300 K, while the excitation maximum is at 220 nm. The decay curve of the emission is single exponential with a decay time of 570 ps at 4.2 K. The emission spectrum of BaS04 Pb demonstrates a broad band peaking at 340 nm with an excitation maximum at 220 nm, while in SrS04 Pb the luminescence band has a maximum at 380 nm. hi natural barite and anhydrite samples we detected several narrow UV bands, which may be connected with Pb emission, but for confident conclusion additional study is needed. In any case, Pb participation in natural sulfates liuninescence has to be taken into consideration. 

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 directly sulfonated CDs were the second family of compounds studied. The substituent was introduced, after multiple synthetic steps, at the C6 position with a metabolically stable C-S bond. Like the sulfate derivatives, the sulfonates have the negative charge of the substituent in proximity to the carbohydrate backbone. 

Mora and coworkers201 studied the in vivo interaction, in mice, of toxic levels of cationic macromolecules with the carboxyl and sulfate derivatives of polyglucose. Toxic levels of polymyxin, protamine, streptomycin, and neomycin could be counteracted, if the synthetic macroanions were injected five to ten minutes after administration of the proteins. Subcutaneous administration of the anionic polyglucoses prior to intra-peri toneal injection of toxic levels of basic proteins afforded protection to the mice, and also demonstrated that the animals could survive, even when the two injections were by different routes. 

The bicyclic guanidinium tetramer 43 was first reported as a possible binder for helical oligonucleotides. Initial studies with 43 and sulfate anions showed that the tetramer formed double-helical dimers around sulfate counterions [69]. Despite the initial proposal of using this receptor for membrane transport of oligonucleotides, all subsequent work on 43 has been conducted on helical peptides. For example, the binding of 43 with several synthetic peptides caused an increase in the helicity and helical stability of the peptides in 10% water/methanol [70]. The peptide containing four Asp derivatives showed the... 

Several recent publications describe cleavage of 1,3,2-dioxathiolane. S -dioxides (cyclic sulfates) by halide nucleophiles that furnish halohydrines, which can be used as synthetic intermediates, primarily for preparation of corresponding epoxides or for further reactions with nucleophiles (Table 6). Similar reactions with chloride have been studied for 1,3,2-dioxathiolane J-oxides (cyclic sulfites) <1996ACS832>. 

Although sulfation of dextran is an easy synthetic step, most of the studies directed towards biological activity of dextran sulfate are carried out with commercially available products. The DS of these derivatives is usually rather high. The DS of the most widely applied dextran sulfate from Sigma is 2.3. A typical 13C NMR spectrum of a commercial dextran sulfate is shown in Fig. 12. The spectrum confirms the high degree of sulfation and reveals com-... 

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