Biomedical subjects

I I Stepuro

Publications and source records attributed to I I Stepuro.

40 records · Page 3Linked to original sources

PubMedDate not supplied

[Changes in serum albumin conformation following exposure to ultraviolet radiation].

Rapid photolysis of one (the most labile) disulfide bridge in bovine and human serum albumines resulted from the sensitizing action of 212 and 214 tryptophane residues, correspondingly, decomposing practically simultaneously with the disulfide bond. This effect was not observed in 6-8 M guanidine. Conformational rearrangement of the protein globule accompanied by a decrease of the exposed arginine residues was observed after the break of the albumine disulfide bond on NaBH4 by ultraviolet, the exposed lisine residues being unaltered. The intensity of 1,8-anilinonaphtalenosulfonate (ANS) fluorescence decreased by 60-70% after the reduction of the disulfide bond due to the arginine residues being unexposed for the chromophore.

Animals↗

PubMedDate not supplied

[Kinetics of ethanol-induced lysis of human erythrocytes].

Hemolysis of human erythrocytes induced by the high ethanol concentrations involves several stages, which are reflected by the kinetic curves of hemolysis. These stages are of colloid-osmotic nature. Ethanol denaturation of membrane proteins and their subsequent aggregation can be responsible for appearance of defects, pores, in the erythrocyte membrane. About 15 ethanol molecules participate in formation of one pore. Sucrose weakly diffusing through the formed pores inhibits the ethanol-induced hemolysis of erythrocytes. On the contrary, the hyperosmotic contraction of erythrocytes in the NaCl- or KCl-containing medium increases the efficiency of the hemolysis. The maximum stability of the erythrocytes to the ethanol action is at the pH 7.2-7.3.

Erythrocyte Membrane↗

PubMedDate not supplied

[Thermostability of erythrocyte membranes in the presence of ethanol].

Differential scanning microcalorimetry was used to show a destabilizing effect of ethanol on erythrocyte membrane proteins. The thermostability of the membrane cooperative unit, with the main protein being band 3 integral protein, was decreased most significantly, which was probably related to a disturbance in protein--lipid complementary. At sufficiently high ethanol concentrations the denaturational changes in the membrane proteins resulted in lysis of red blood cells preceeding at several stages: morphological changes in cells, as well as swelling and the lysis, proper. The activation energy of the ethanol-induced lysis as determined from the temperature dependence of the apparent hemolysis rate constant was equal to 150 +/- 20 kJmol-1 at 5.1 M ethanol concentration. This corresponded to the activation energy of the protein denaturation.

Calorimetry, Differential Scanning↗

PubMedDate not supplied

[Nonenzymatic covalent modification of human hemoglobin by pyridoxal-5-phosphate under the effect of visible light].

Under the action of visible light, PLP with apo-, oxy- and deoxy-Hb at 4-20 degrees C and neutral pH produced adducts stable to dialysis and Sephadex gel filtration. The stable adduct formation enhanced with an increase in radiation intensity and/or irradiation time. Under light, production of stable adducts occurred most effectively for apo-Hb and was significantly slowed down in the case of met-Hb as well as in the presence of an electron acceptor, methylene blue. PLP-Hb adducts possessed intense fluorescence coinciding in properties with the fluorescence of stable PLP adducts obtained after Schiff base reduction by NaBH4. Stable adduct formation is assumed to proceed owing to Schiff base aldimin link reduction by photoejected electrons. During isoelectrofocusing of hemoglobins which had formed stable adducts with PLP under light or after NaBH4 treatment of solutions, essentially the same pictures were observed as to the number of new bands and their position in the isoelectroforegram, with the band intensity being different. This is related to the distinctions in the electron seeking properties of the Schiff bases produced by PLP with alpha-NH2 groups of Val-1 and epsilon-NH2 groups of lysine residues of the protein alpha- and beta-chains.

Chromatography, Gel↗