Tag Archives: albumin

Studying the interaction of 2′-5′-oligoadenylate and their analogues with proteins by fluorescence spectroscopy

Z. Yu. Tkachuk1, L. V. Dubey1, V. V. Tkachuk1, L. V. Tkachuk1,
M. Yu. Losytskyy2, V. M. Yashchuk2, І. Ya. Dubey1

1Institute of Molecular Biology and Genetics,
National Academy of Sciences of Ukraine, Kyiv;
2Taras Shevchenko Kyiv National University,Ukraine;
e-mail: ztkachuk@bigmir.net

The interaction of “core” 2′-5′-oligoadenylates (2-5A) and their analogues with proteins albumin, interferon and immunoglobulin G was studied by fluorescence spectroscopy methods. Strong quenching of protein fluorescence (up to 67%) was observed upon interaction of oligoadenylates in concentration of 5×10-5 М with albumin. Investigated compounds quenched the emission of interferon to a lesser extent, whereas no significant fluo­rescence changes occurred upon interaction with immunoglobulin under the same conditions. The level of quenching depended on the structure of 2-5A compounds and decreased with the decrease of their concentration. These data suggest that 2-5A actively bind to albumin and less efficiently to interferon, and practically do not interact with immunoglobulin. Taking into consideration different efficiency of quenching of the fluorescence excited at 280 and 296 nm, the assumption has been made about a possible role of tyrosine and tryptophan in the binding of a given compound to proteins. Possible mechanisms of interaction of oligoadenylates with proteins are discussed.

Antioxidant properties of proteins after freezing-thawing

S. L. Rozanova, E. D. Rozanova, O. A. Nardid

Institute for Problems of Cryobiology and Cryomedicine,
National Academy of Sciences of Ukraine, Kharkiv;
e-mail: sv.rosanova@gmail.com

Experimental data are presented which were obtained under comparative evaluation of influen­ce of different freezing-thawing conditions on antioxidant properties of isolated proteins: human serum albumin, cytochrome с from the horse heart and glucose oxidase from Aspergillus niger. The observed protein antioxidant activity alterations are assumed to be a result of protein conformational changes. The character of freezing-thawing influen­ce on the protein antioxidant activity depends on the molecular structure and cooling conditions.

Comparison of bioactive aldehydes modifying action on human albumin

I. P. Krysiuk, A. J. Knaub, S. G. Shandrenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
е-mail: iryna-kr@yandex.ua

Protein’s postsynthetic modifications are a cause and a consequence of many diseases. Endogenous aldehydes are one of the main factors of these modifications formation. The human albumin’s modification under some aldehydes influence in in vitro experiment has been investigated. Human albumin (20 mM) was incubated with following aldehydes: ribose, glyoxal, methylglyoxal and formaldehyde (20 mM each) and their combinations in 0.1 M Na-phosphate buffer (pH 7.4) with 0.02% sodium azide at 37 °C in the dark for up to 30 days. We have determined the fluorescent properties of the samples, the content of protein’s carbonyl groups and the redistribution of protein’s molecular weight.
The following ratings of aldehydes from the lowest to the highest effect have been obtained. Fluo­rescent albumin adducts formation: formaldehyde, methylglyoxal, ribose, glyoxal; carbonylation of the protein: ribose, formaldehyde, glyoxal, methyl­glyoxal; polymerization of albumin – the formation of intermolecular crosslinks: ribose, methylglyoxal, glyoxal, formaldehyde. The results indicate that these aldehydes have different capability for protein’s modifications. For example, formaldehyde, having the lowest ability to form fluorescent adducts, shows the highest ability to form protein’s intermolecular crosslinks. Therefore, methods and parame­ters in order to evaluate the protein postsynthetic modification intensity have to be chosen correctly according to carbonyl stress peculiarity in order to evaluate the protein’s postsynthetic modification intensity.