Biological Material cysteine

In conclusion it may be said that the examination of the content of cystine and cysteine in biological materials retains its importance for certain purposes even now. The indirect determination of other amino acids also has its importance and advantages. 

The method was also used for the determination of cysteine and glutathi but its application presents, mainly in biological materials, the doubts expressed in the previous paragraphs. For the determination of cystine a method is employed based on the reduction of cystine in an acidic medium with sodium amalgam or on the reaction with sulphite at pH 8-12 according to equation ... 

The third route stems from lanthionine(L)which has been occasionally found in biological materials(17)where could be generated either by condensation of cysteine with serine or of cysteine with aminoacrylate obtained by a... 

The synthesis and characterization of materials showing biological activity similar to that of GTF isolated from yeast is a logical objective. As already mentioned, Mertz found aqua and similar complexes of chromium to be more active than chelates with strong ligands. An exception to this was an unspecified cysteine complex,1193 prepared by C. L. Rollinson, which showed marked, but erratic, behaviour in GTF tests. Further investigation of this observation would be interesting, particularly as the crystal structure of a cysteine complex is now known.1185... 

A block copolymer effective as a controlled release agents of biologically active materials have been prepared. This agent consisted of ethylene oxide-propylene sulfide-ethylene oxide teipolymer that had been end-capped with a selected cysteine-containing peptide. These materials resist degradation prior to reaching their intended targets because they behave as multilamellar vesicles. 

Pos et ai, 1998). Colored dissolved organic material is frequently involved in such processes. Laboratory irradiation has confirmed that cysteine and cystine are efficient precursors of CS2 and that OH radicals are likely to be important intermediates (Xie et ai, 1998), but it is also likely that some of these sulfur gases are produced directly by biological processes. Ocean waters appear to be supersamrated in carbon disulfide and capable of yielding —0.1 Tg(S) yr (Xie and Moore, 1999). 

The choice of working electrode material is an important factor in amperometric detection. For catechols and similar substances, such as phenolic acids, electrodes made of glassy carbon have shown good performances. Other good detectable and biological important substances include thiols and disulfides (e.g., cysteine, glutathione, and their disulfides which... 

Since our intent was to use the competitive A-B ELISA to quantify 3-Cys-A adducts formed in biological samples at unknown and perhaps variable levels of protein modification, experiments were conducted to determine the effect of adduct substitution level on quantification. Standards of known substitution level were prepared by derivatizing 9,000 g liver supernatant with various concentrations of [3H]NAPQI. After extensive dialysis to remove noncovalently bound materials, protein concentrations were determined and the substitution level of each standard was determined by scintillation counting. These synthetic standards, which ranged from 0.5 to 30 nmol 3-(cystein-S-yl)[3H]acetaminophen per mg protein, were analyzed in the competitive immunoassay. When the data were plotted with percent inhibition as a function of protein concentration, the results show an ordered family of inhibition curves where the most highly substituted proteins were the... 

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