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Wyświetlanie 1-4 z 4
Tytuł:
Atomic force microscopy studies of the adhesive properties of DPPC vesicles containing β-carotene
Autorzy:
Augustyńska, Dominika
Jemioła-Rzemińska, Małgorzata
Burda, Kvetoslava
Strzałka, Kazimierz
Powiązania:
https://bibliotekanauki.pl/articles/1039795.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
atomic force microscopy
dipalmitoylphosphatidylcholine
β-carotene
liposome adhesion
thermal transition
Opis:
A role of carotenoids as modulators of physical properties of model and biological membranes has been already postulated. However, there is a lack of information on the influence of these pigments on interactions between the lipids which form such membranes. This paper applies atomic force microscopy (AFM) in to study the effects of β-carotene on the adhesion properties of DPPC multilamellar liposomes. This allowed us to gain, for the first time, a direct insight into the interactions between the components in model systems on a molecular level. We observe that the adhesive forces in DPPC multilamellar liposomes containing 1mol% of β-carotene decrease exponentially with increasing temperature, and that at about 37°C they diminish. In the case of pure liposomes the decline in adhesion is of a different nature and the adhesive forces disappear at 34°C. The adhesive forces are about 5 times higher at 31°C in the presence of β-carotene than in its absence. However, measurements using differential scanning calorimetry (DSC) showed a shift of the lamellar-to-undulled-lamellar phase transition toward lower temperatures by about 0.8±0.2°C in a system containing β-carotene. The enthalpy changes (ΔH) of this transition are similar for both systems. For the main transition, gel-to-liquid crystalline, the peak is shifted by about 0.5±0.1°C, and ΔH decreases by about 30% in liposomes treated with β-carotene in comparison to pure liposomes. Our results suggest increased cooperation between liposome components in a system with enriched β-carotene, which cause a change in phase transition temperatures. Moreover, these interactions are very sensitive to temperature.
Źródło:
Acta Biochimica Polonica; 2012, 59, 1; 125-128
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antioxidant effects of carotenoids in a model pigment-protein complex
Autorzy:
Fiedor, Joanna
Sulikowska, Aleksandra
Orzechowska, Aleksandra
Fiedor, Leszek
Burda, Květoslava
Powiązania:
https://bibliotekanauki.pl/articles/1039774.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
carotenoid
antioxidant
stability
chemical oxidation
Opis:
The effect of carotenoids on stability of model photosynthetic pigment-protein complexes subjected to chemical oxidation with hydrogen peroxide or potassium ferricyanide was investigated. The oxidation of carotenoid-less and carotenoid-containing complexes was conducted in the presence or absence of ascorbic acid. The progress of the reactions was monitored by use of absorption and fluorescence spectroscopy. Our results show that carotenoids may significantly enhance the stability of photosynthetic complexes against oxidation and their protective (antioxidant) effect depends on the type of the oxidant.
Źródło:
Acta Biochimica Polonica; 2012, 59, 1; 61-64
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic force measurements of avidin-biotin and streptavdin-biotin interactions using AFM
Autorzy:
de Odrowąż Piramowicz, Marzena
Czuba, Paweł
Targosz, Marta
Burda, Kvĕtoslava
Szymoński, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1041274.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
atomic force microscopy
rupture force
loading rate
streptavidin
avidin
biotin
dissociation rate
Opis:
Using atomic force microscopy (AFM) we performed dynamic force measurements of the adhesive forces in two model systems: avidin-biotin and streptavidin-biotin. In our experiments we used glutaraldehyde for immobilization of (strept)avidin on the tip and biotin on the sample surface. Such interface layers are more rigid than those usually reported in the literature for AFM studies, when (strept)avidin is coupled with biotinylated bovine albumin and biotin with agarose polymers. We determined the dependence of the rupture forces of avidin-biotin and streptavidin-biotin bonds in the range 300-9600 pN/s. The slope of a semilogarithmic plot of this relation changes at about 1700 pN/s. The existence of two different regimes indicates the presence of two activation barriers of these complexes during the dissociation process. The dissociation rates and activation energy barriers, calculated from the Bell model, for the avidin-biotin and streptavidin-biotin interactions are similar to each other for loading rates >1700 pN/s but they are different from each other for loading rates < 1700 pN/s. In the latter case, the dissociation rates show a higher stability of the avidin-biotin complex than the streptavidin-biotin complex due to a larger outer activation barrier of 0.8 kBT. The bond-rupture force is about 20 pN higher for the avidin-biotin pair than for the streptavidin-biotin pair for loading rates < 1700 pN/s. These two experimental observations are in agreement with the known structural differences between the biotin binding pocket of avidin and of streptavidin.
Źródło:
Acta Biochimica Polonica; 2006, 53, 1; 93-100
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of low doses of gamma rays on the stability of normal and diabetic erythrocytes
Autorzy:
Kaczmarska, Magdalena
Kopyściańska, Zofia
Fornal, Maria
Grodzicki, Tomasz
Matlak, Krzysztof
Korecki, Józef
Burda, Květoslava
Powiązania:
https://bibliotekanauki.pl/articles/1039830.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
γ rays
diabetes
absorption spectroscopy
Mössbauer spectroscopy
hemoglobin
erythrocytes
hemolysis
Opis:
We studied the influence of low doses of γ radiation (from 0.04 to 1.8 mGy) on the stability of human red blood cells (RBC) from healthy donors and diabetic patients using absorption spectroscopy. Because of the alteration of many enzymatic pathways in diabetic RBCs resulting in strong modification of the lipid and protein membrane components one could expect that the ionizing γ-radiation should influence the stability of the healthy and diabetic cells in a different way. Indeed, distinct discontinuities and monotonic changes of hemolysis detected in the healthy and diabetic RBCs suggest that various enzymatic and chemical processes are activated in these membranes by γ radiation. Mössbauer measurements showed that only the highest applied dose of γ radiation caused modification of hemoglobin in both types of RBCs.
Źródło:
Acta Biochimica Polonica; 2011, 58, 4; 489-496
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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