Wyniki wyszukiwania - Biblioteka Nauki

1

Coulometric titration of disulfides with electrogenerated chlorine

100%

Ciesielski W. , Skowron M.

Chemia Analityczna

|

2005

|

tom Vol. 50, No. 1

47-53

EN

The coulometric titration of some disulficles with anodically generated chlorine using the biamperometric end-point detection is presented. Chlorine breakes the disulfide bond and asulfonic acid is formed. The range of determination is 0.50-3.75 μmol for 2,2-dithiodi-glycolic acid, 0.375-1.50 μmol for 3.3'-dithiodipropionic acid, 1.00-2.50 μmol forcystamine dihydrochloride and 0.50-2.75 μmol for L-cystine. The titrations were performed in solutions containing 0.5 mol L-1H2SO4 and various amounts of NaCl. The error for all determinations is below 1 %.

PL

Przedstawiono kulometryczne miareczkowanie disiarczków anodowo generowanym chlorem z zastosowaniem biamperometrycznej detekcji punktu końcowego. W reakcji z chlorem następuje rozerwanie wiązania disiarczkowego i powstaje kwas sulfonowy. Zakres ozna-czalności wynosi 0.50-3.75 μmoli dla kwasu 2,2'-ditiodiglikolowego, 0.375-1.50μ mola dla kwasu 3,3'-ditiodipropionowego, 1.00-2.50 μmoli dla dichlorowodorku cystaminy i 0.50-2.75 μmoli dla L-cystyny. Miareczkowania były prowadzone w roztworach zawierających 0.5 mol L-1H2SO4 i różne ilości NaCl. Opracowana metoda umożliwia oznaczanie disiarczków z błędem poniżej 1%.

2

Plasma levels of total, free and protein bound thiols as well as sulfane sulfur in different age groups of rats

100%

Iciek M. , Chwatko G. , Lorenc-Koci E. , Bald E. , Wlodek L.

Acta Biochimica Polonica

|

2004

|

tom 51

|

nr 3

EN

The redox status of plasma thiols can be a diagnostic indicator of different pathological states. The aim of this study was to identify the age dependent changes in the plasma levels of total, free and protein bound glutathione, cysteine and homocysteine. The determination was conducted in plasma of three groups of rats: 1) young (3-month-old), 2) middle aged (19-month-old), and 3) old (31-month-old). Total levels of glutathione, cysteine and homocysteine and their respective free and protein-bound fractions decreased with age. The only exception was a rise in free homocysteine concentration in the middle group, which indicates a different pattern of transformations of this thiol in plasma. The drop in the level of protein-bound thiols suggests that the antioxidant capacity of plasma diminishes with age, which, consequently, leads to impaired protection of -SH groups through irreversible oxidation. The plasma sulfane sulfur level also declines with age, which means that aging is accompanied by inhibition of anaerobic sulfur metabolism.

3

Dyeing performance of a new disazo disulphide bis(ethylsulphone-monochlorotriazine) reactive dye on cotton

84%

Youssef Y. A. , Mousa A. A.

Polish Journal of Applied Chemistry

|

2003

|

tom Vol. 47, nr 4

275-285

EN

A novel disazo reactive dye of a temporarily high molecular structure containing disulphide bis(ethylsulphone-monochlorotriazine) reactive system has been synthesised and applied to cotton. By virtue of the characteristic disazo disulphide bis(ethylsulphone) dye structure, a good substantivity was observed at the neutral exhaust dyeing conditions. Subsequently, the results assessed for the alkaline dyeing conditions indicate that the dye vinylsulphone-monochlorotriazine reactive system confers a high fixation efficiency for this type of disazo reactive dye. The results also indicate that the high fastness properties were obtained.

4

Cysteine-induced changes of low molecular sulfhydryl/disulfide ratio in rat lymphoid cells

84%

Krzystyniak K. , Fournier M. , Ryzewski J.

Archivum Immunologiae et Therapiae Experimentalis

|

1989

|

tom 37

|

nr 1-2

5

Campylobacter protein oxidation influences epithelial cell invasion or intracellular survival as well as intestinal tract colonization in chickens

67%

Lasica A. M. , Wyszynska A. , Szymanek K. , Majewski P. , Jagusztyn-Krynicka E. K.

Journal of Applied Genetics

|

2010

|

tom 51

|

nr 3

EN

The Dsb family of redox proteins catalyzes disulfide bond formation and isomerization. Since mutations in dsb genes change the conformation and stability of many extracytoplasmic proteins, and since many virulence factors of pathogenic bacteria are extracytoplasmic, inactivation of dsb genes often results in pathogen attenuation. This study investigated the role of 2 membrane-bound oxidoreductases, DsbB and Dsbl, in the Campylobacter jejuni oxidative Dsb pathway. Campylobacter mutants, lacking DsbB or Dsbl or both, were constructed by allelic replacement and used in the human intestinal epithelial T84 cell line for the gentamicin protection assay (invasion assay) and chicken colonization experiments. In C. coli strain 23/1, the inactivation of the dsbB or dsbl gene separately did not significantly affect the colonization process. However, simultaneous disruption of both membrane-bound oxidoreductase genes significantly decreased the strain's ability to colonize chicken intestines. Moreover, C. jejuni strain 81-176 with mutated dsbB or dsbI genes showed reduced invasion/intracellular survival abilities. No cells of the double mutants (dsbB⁻ dsbI⁻) of C. jejuni 81-176 were recovered from human cells after 3 h of invasion.

6

Oxidizability of cysteine and short cysteine-containing peptides by molecular oxygen

67%

Dorcak V. , Mader P. , Vesela V. , Fedurco M. , Sestakova I.

Chemia Analityczna

|

2007

|

tom Vol. 52, No. 6

979-988

EN

Rate of oxidation of cysteine. y-glutamylcysteine. cysteinylglycine and reduced glutathione by molecular oxygen has been studied polarographically in alkaline buffers by foliowing the time changes in anodic and cathodic limiting currents of the SH- and SS-groups, respectively. Oxidation of thiols proceeds considerably faster in contact with metallic mercury. Obtained results have been supported by Raman spectroscopy measurements.

PL

Badano polarograficznie szybkość utleniania cysteiny, gamma-glutamylocysteiny. cystci-nogiicyny i zredukowanego glutationu, tlenem cząsteczkowym w roztworach alkalicznych, śledząc zmiany czasu w anodowym i katodowym prądzie granicznym, odpowiednio dla grup SH- i SS-. W obecności metalicznej rtęci utlenianie tioli przebiegało znacznie szybciej. Otrzymane wyniki potwierdzono za pomocą spektroskopii Ramana.