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Wyszukujesz frazę "spectrophotometry" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Mechanism of peroxynitrite interaction with cytochrome c.
Autorzy:
Gębicka, Lidia
Didik, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/1043459.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
cytochrome c
radiolysis
peroxynitrite
stopped-flow spectrophotometry
Opis:
Kinetics of the reaction of peroxynitrite with ferric cytochrome c in the absence and presence of bicarbonate was studied. It was found that the heme iron in ferric cytochrome c does not react directly with peroxynitrite. The rates of the absorbance changes in the Soret region of cytochrome c spectrum caused by peroxynitrite or peroxynitrite/bicarbonate were the same as the rate of spontaneous isomerization of peroxynitrite or as the rate of the reaction of peroxynitrite with bicarbonate, respectively. This means that intermediate products of peroxynitrite decomposition, ·OH/·NO2 or, in the presence of bicarbonate, CO3-·/·NO2, are the species responsible for the absorbance changes in the Soret band of cytochrome c. Modifications of the heme center of cytochrome c by radiolytically produced radicals, ·OH, ·NO2 or CO3-·, were also studied. The absorbance changes in the Soret band caused by radiolytically produced ·OH or CO3-· were much more significant that those observed after peroxynitrite treatment, compared under similar concentrations of radicals. ·NO2 produced radiolytically did not interact with the heme center of cytochrome c. Cytochrome c exhibited an increased peroxidase-like activity after reaction with peroxynitrite as well as with radiolytically produced ·OH, ·NO2 or CO3-· radicals. This means that modification of protein structure: oxidation of amino acids and/or tyrosine nitration, facilitates reaction of H2O2 with the heme iron of cytochrome c, followed by reaction with the second substrate.
Źródło:
Acta Biochimica Polonica; 2003, 50, 3; 815-823
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations
Autorzy:
Rahman, Nafisur
Azmi, Syed
Powiązania:
https://bibliotekanauki.pl/articles/1041343.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
pharmaceutical formulations
spectrophotometry
potassium hydroxide
validation
nifedipine
ammonium molybdate
Opis:
Two simple, sensitive and economical spectrophotometric methods were developed for the determination of nifedipine in pharmaceutical formulations. Method A is based on the reaction of the nitro group of the drug with potassium hydroxide in dimethyl sulphoxide (DMSO) medium to form a coloured product, which absorbs maximally at 430 nm. Method B uses oxidation of the drug with ammonium molybdate and subsequently reduced molybdenum blue is measured at 830 nm. Beer's law is obeyed in the concentration range of 5.0-50.0 and 2.5-45.0 µg ml-1 with methods A and B, respectively. Both methods have been successfully applied for the assay of the drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. The reliability and the performance of the proposed methods are established by point and interval hypothesis tests and through recovery studies.
Źródło:
Acta Biochimica Polonica; 2005, 52, 4; 915-922
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reactions of Pseudomonas aeruginosa pyocyanin with reduced glutathione
Autorzy:
Cheluvappa, Rajkumar
Shimmon, Ronald
Dawson, Michael
Hilmer, Sarah
Le Couteur, David
Powiązania:
https://bibliotekanauki.pl/articles/1040717.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
Pseudomonas aeruginosa pyocyanin
superoxide dismutase
catalase
spectrophotometry
nuclear magnetic resonance imaging
glutathione
cystic fibrosis
oxidative stress
Opis:
Pseudomonas aeruginosa is the most common cause of chronic and recurrent lung infections in patients with cystic fibrosis (CF) whose sputa contain copious quantities of P. aeruginosa toxin, pyocyanin. Pyocyanin triggers tissue damage mainly by its redox cycling and induction of reactive oxygen species (ROS). The reactions between reduced glutathione (GSH) and pyocyanin were observed using absorption spectra from spectrophotometry and the reaction products analysed by nuclear magnetic resonance imaging. Pyocyanin reacted with GSH non-enzymatically at 37°C resulting in the production of red-brown products, spectophotometrically visible as a 480 nm maximum absorption peak after 24 h of incubation. The reaction was concentration-dependent on reduced glutathione but not on pyocyanin. Minimizing the accessibility of oxygen to the reaction decreased its rate. The anti-oxidant enzyme catalase circumvented the reaction. Proton-NMR analysis demonstrated the persistence of the original aromatic ring and the methyl-group of pyocyanin in the red-brown products. Anti-oxidant agents having thiol groups produced similar spectophotometrically visible peaks. The presence of a previously unidentified non-enzymatic GSH-dependent metabolic pathway for pyocyanin has thus been identified. The reaction between pyocyanin and GSH is concentration-, time-, and O2-dependent. The formation of H2O2 as an intermediate and the thiol group in GSH seem to be important in this reaction.
Źródło:
Acta Biochimica Polonica; 2008, 55, 3; 571-580
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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