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DNA loops after cell lysis resemble chromatin loops in an intact nucleus

K. S. Afanasieva, V. V. Olefirenko, A. V. Sivolob

ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, Ukraine;

The comet assay has proved itself to be not only a method of detection of DNA damages at the level of individual cells but also an approach for investigation of spatial organization of DNA loop domains in nucleoids. Usually, those nucleoids are obtained after cell lysis in high-salt buffer (e. g. 2.5 M NaCl) with a detergent: these conditions ensure the removal of cell membranes and most of the chromatin proteins, while supercoiled DNA loop domains remain untouched. In this work, we tested the comet assay applied to nucleoids obtained in low-salt solution (1 M NaCl). These nucleoids keep most of the histones and thus contain the loops resembling the chromatin loops to a greater extent. It was shown that, despite some quantitative differences, the most general features of the kinetics of DNA exit are about the same for nucleoids obtained in high- and low-salt conditions. It can be concluded that the DNA loops in high-salt nucleoids can be efficiently used to investigate the spatial DNA organization in chromatin.

Calix[4]arene С-956 selectively inhibits plasma membrane Са(2+),Mg(2+)-АТРase in myometrial cells

Т. O. Veklich1, O. A. Skrabak1, Yu. V. Nikonishyna1, R. V. Rodik2, V. I. Kalchenko2, S. O. Kosterin1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv;

Using enzymatic assays and kinetic analysis, we demonstrated that 100 µM calix[4]arene C-956 (5,11,17,23-tetra(trifluoro)methyl-(phenylsulfonylimino) methylamino-25,27-dioctyloxy-26,28-dipropoxycalix[4]arene) had the most significant inhibitory effect on the plasma membrane Са2+,Mg2+-АТРase activity compared to effects of other calix[4]arenes, and had no effect on specific activities of other membrane ATPases. Using confocal microscopy and fluorescent probe fluo-4, we observed an increase of the intracellular level of Ca2+ after application of calix[4]arene C-956 to immobilized myocytes. Analysis of the effect of calix[4]arene C-956 on the hydrodynamic diameter of myocytes demonstrated that application of calix[4]arene C-956 solution decreased this parameter by 45.5 ± 9.4% compared to control value similarly to the action of uterotonic drug oxytocin.

Influence of organic solvents on the furin activity

T. V. Osadchuk1, O. V. Shybyryn1, A. V. Semyroz1, V. K. Kibirev1,2

1Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;

Furin belongs to a family of calcium-dependent serine proprotein convertases, which transform the inactive protein precursors into mature polypeptides. In model experiments, we studied the effect of organic solvents such as acetone, dimethyl sulfoxide (DMSO), dioxane, isopropanol and ethanol on the furin activity. Furin was found to retain up to 88% of its initial activity in the presence of DMSO, whereas in the presence of acetone only 30%. Organic solvents formed the following decreasing sequence of their effects on furin: acetone> isopropanol> ethanol> dioxane> dimethyl sulfoxide. The relationship between the residual furin activity and solvent parameters such as relative polarity, dipole moment and log P were investigated. The effect of the organic solvent appeared not to correlate with any of the listed characteristics. Laidler-Sсatchard’s graphs, which according to a theory must be linear, demostrated non-linearity. These results indicate that not only electrostatic interactions play an important role in the studied enzymatic reaction but also other factors, e.g. hydrophobic contacts, hydrogen bonds can influence furin catalysis. This seems relevant for further research in this area.

Influence of chemical reagents and UV irradiation on the activity of Penicillium canescens α-galactosidase

N. V. Borzova, L. D. Varbanets

Danylo Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv;

Investigations of the influence of chemical and physical factors on the conformational and functional properties of enzymes make a significant contribution to the study of the mechanism of action of industrially important proteins. The aim of the work was to evaluate the effect of chemical reagents and UV irradiation on the catalytic properties of Penicillium canescens α-galactosidase. Enzyme activity was assessed with p-nitrophenyl-α-D-galactopyranoside. Studies of the functionally active glycosidase groups were carried out on the basis of inhibitory and kinetic analysis using Dixon and Luinuiver-Burke methods with help of specific chemical reagents. A significant decrease in the activity of α-galactosidase in the presence of carbodiimi­des, diethylpyrocarbonate, the reagents on sulfhydryl groups was shown. A UV-induced decrease in enzyme activi­ty in the dose range of 900-7200 J/m2 was noted. Based on the data obtained, the imidazole group of histidine, carboxyl groups of C-terminal amino acids and the SH-groups of cysteine are assumed to play an important role in the manifestation of the activity of P. canescens α-galactosidase.

Biochemical aspects of the combined use of taxanes, irradiation and other antineoplastic agents for the treatment of anaplastic thyroid carcinoma

V. M. Pushkarev, O. I. Kovzun, V. V. Pushkarev, B. B. Guda, M. D. Tronko

SI V. P. Komisarenko Institute of Endocrinology and Metabolism, NAMS of Ukraine, Kyiv;

The review summarizes the results of the cycle of own research and literature data on biochemical mechanisms of combined action of taxanes with γ-irradiation and other antineoplastic agents on one of the most aggressive types of human cancer – anaplastic thyroid carcinoma. Antagonistic interplay between taxanes and irradiation at the level of apoptotic mechanisms and regulators of the cell cycle are discussed. The effectiveness and prospects of using low concentrations of taxanes and low doses of fractional γ-irradiation are substantiated. Attention is paid to the role of inflammation and its key factor – NF-κB in the genesis of thyroid carcinomas and their treatment. Directions for further research are outlined.

Hematologic features of beta-globin gene mutation type (βo) with homozygous beta thalassemia

Gülüzar Özbolat, Abdullah Tuli

Cukurova University, Faculty of Medicine Department of Medical Biochemistry, Adana, Turkey;

β-Tthalassemia is common genetic disorders in Turkey that characterized by the reduced synthesis (β+) or absence (βo) of the β-globin chains in the HbA molecule. In this study, we aimed to determine the effect of the mutation type of the β-globin gene on hematological values in homozygous β-thalassemia. This retrospective study was undertaken by Prenatal Diagnosis Centres of Cukurova University Medical Biochemistry at Adana. We evaluated 60 homozygous by implementing DNA sequencing analysis for mutations undetectab­le by conventional methods. 30 patients with βo [FSC 44/ C-A] mutations and the other 30 patients with βo [(IVS-II-1(G>A), CD39 (C>T), Cd8 (-AA) Cd39 C> T and CD36/37 (–T)] mutations, totally 60 patients were included in the study. Erythrocyte indices, HbF, HbA2 levels were compared between the two groups. FSC 44/(-C) mutations were detected in patients. Hb, Hct, MCV in this group values were statistically lower than in patients with other detected mutations (P < 0.05). Between the two groups, there is no statistically different RBC, MCH, MCHC, HbF, HbA2 levels (P ˃ 0.05). For the first time in this study, it was found that the Hb, Hct and MCV value of the persons who carried the FSC 44/(-C) mutation were significantly lower than the persons who carrying other mutations. Between the two groups, there was no statistical difference in RBC, MCH, MCHC, HbF and HbA2 levels. Awareness of FSC/44 mutation, which may have a heterogeneous clinical presentation, is required. We herein present the hematologic findings of a Turkish population carrying this mutation. This will also help to make a diagnosis.