Serum thiols

Treatment of RA patients with various drugs was shown to affect free radical production by phagocytic cells. It was found that the therapy with gold compounds [252] and piroxicam [237] diminished superoxide production in RA patients. Surprisingly, Hurst et al. [253] reported that successful therapy with penicillamine or sodium aurothiomalate is accompanied by an increase in superoxide production and serum thiol levels. The mechanism of this phenomenon is unknown. Mur et al. [254] demonstrated that antirheumatic medication of RA patients caused reducing cytokine priming of superoxide generation. 

It is also of interest to note that red blood cells from rheumatoid arthritis patients were found to have less than normal Cu-Zn SOD [74] and the decrease in Cu-Zn SOD significantly correlated with increased serum thiol. 

Lewis, S.D., Misra, D.C. and Shafer, J.A. (1980) Determination of interactive thiol ionizations in bovine serum albumin, glutathione, and other thiols by potentiometric difference titration. Biochemistry, 19, 6129-6180. 

A reversible, direct fluoroimmunosensor for human serum albumin (HS A) measurement has been described by Bright et al.(m> Antibody Fab fragments are first immobilized on small quartz plates by hinge-region thiols, and then dansylated. The immunosensor is formed by attaching the quartz plates with bound Fab to the distal end of a bifurcated fiber-optic probe, which transmits both the excitation and emission. Binding of ffSA to the immunosensor results in a three- to five-fold enhancement of dansyl fluorescence. The sensor can be reused up to 50 times, with a detection limit of about 1.8 x 10-8 M, and a somewhat limited dynamic range. 

Determination of various analgesic and antipyretic pharmaceuticals on reversed phase has included not only the analysis of serum levels of aspirin, salicylic acid and salicyluric acid using acidified acetonitrile (557), or methanol (338), but also suUinpyrazone under isocratic conditions (339), and 6-chloro-a-methylcarbazole-2-acetic acid (340). The polar thiol metabolites of acetaminophen were analyzed by RPC and the method was found to be superior to other chromatographic techniques used in this analysis (341). 

The relatively acidic thiol on serum albumin forms a fairly stable S-nitroso adduct with nitric oxide, which may serve to preserve and carry NO throughout the circulatory system [162,163]. Bacterial toxins released in toxic-shock syndrome induce excessive NO-synthase activity in macrophages. The resulting arterial expansion may induce the cardiovascular collapse associated with toxic shock syndrome [164]. Nitrous acid reacts with DNA to form dG-N2-dG interstrand crosslinks at the sequence 5 CG [165]. NO can also deaminate cytidine [166] and deoxyguanosine [167] and so may function as a mutagen. The rate law for NO reacting with O2 has been measured electrochemically as [168] ... 

For the modification of the gold surface different chemical and biological substances (dodecanethiol, lectins, dextran sulfate DS, with the mass of 5 kDa and polyelectrolytes) were used. The mercaptane layer was formed in ethanol atlO" M concentration of thiol. Polyaniline hydrochloride (PAH), Aldrich , USA, was used to cover the transducer surface by a water insoluble polymer. Lectins from Phaseolus vulgaris (PLA), Solanum tuberosum (STA), Helix pomatia (HPA) and Tuberosum vulgaris (WGA) were immobilized on the surface pre-treated with dodecanethiol or PAH. These lectins were used for the immobilization of glycoproteins. Blocking of the free binding sites was carried out with 1% bovine serum albumin (BSA). 

Proteins like serum albumin have cysteine residues that can also stabilize Au NPs through chemisorption of the thiol groups [150]. 

Bovine serum albumin is denatured at pH 4 because of repulsion of acidic amino acids (Haurowitz 1963). As with a-lactalbumin, failure to measure the heat of denaturation for bovine serum albumin at pH 3 indicates that it is already unfolded by acid (de Wit and Klarenbeek 1984). It is more stable at pH 7.5 than at pH 6 because of increased activity of thiol groups at high pH. Denaturation is enhanced more by calcium ions than by other anions (Shimada and Matsushita 1981). Fatty acids appear to stabilize bovine serum albumin against heat denaturation (Gumpen et al 1979). 

FIG. 9 Serum PSA, thiobarbituric acid substances (TBARS), and thiols in prostate cancer cases and controls ( p < 0.05). (Lycopene, tomatoes and health New Perspectives 2000. Reprinted from Lycopene and the prevention of chronic diseases. Major findings from five international conferences. 2002. A.V. Rao, D. Heber, eds., p. 23. By permission of Caledonian Science Press.)... 

Serum proteins from cell culture medium OEG-thiol... 

In 2001, Van Orden et al. reported the first biologically relevant FRET investigation using QDs as energy donors.83 They conjugated biotinylated bovine serum albumin (bBSA) to water-soluble CdSe-ZnS-TA QDs via a thiol linkage with 2-iminothiolane. The acceptor was streptavidin covalently labeled with tetra-methylrhodamine (TMR). Once the avidin-biotin interaction took place, a decrease in the QD luminescence and an increase in the TMR luminescence were observed, which was attributed to FRET between QD and TMR. Although no time-resolved fluorescence experiments were carried out and no estimates for the separation distance... 

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