Biomedical subjects

L P Budnikova

Publications and source records attributed to L P Budnikova.

4 recordsLinked to original sources

PubMedDate not supplied

[Stabilization of diluted aqueous solutions of horseradish peroxidase].

Effects of pH, enzyme concentration, and various supplements on the catalytic activity, temperature stability, and secondary structure of horseradish peroxidase (HRP) were studied in diluted aqueous solutions. In 5.0 mM citrate-phosphate buffer (pH 4.2) at 55 degrees C and infinite dilution, HRP was inactivated with a rate constant of 2.86 x 10(-3) s-1. CaCl2, BSA, and glycerol caused protective effects, whereas KCl, LiCl, maltose, PEG-6000 (at a concentration above 3%), Triton X-100, ethanol, and Kathon CG had an opposite effect and altered the secondary structure of HRP. Two HRP-stabilizing media: the "glycerol-based" one containing 10% ethanol and 20% glycerol, or the "protein-based" one containing 0.1% Kathon CG and 0.2 g/l of BSA in 50.0 mM Tris-HCl buffer (pH 7.2) supplemented with 50 mM CaCl2 were developed, and the stability of HRP (0.36 nM) and its immunoglobulin, cortisol, and progesterone conjugates were compared in these two media. The protein-based medium displayed a greater stabilizing effect particularly on HRP-steroid conjugates.

Buffers↗

PubMedDate not supplied

[Polymerization of horseradish peroxidase in the presence of inorganic adsorbents].

Efficiencies of binding between horseradish peroxidase (HRP) and its polymers (HRPp) with inorganic adsorbents (precipitated and coprecipitated) were studied. In aqueous solutions, HRP efficiently adsorbed to aluminum oxide and the coprecipitated sorbent (composed of calcium orthophosphate, magnesium hydroxide, and aluminum hydroxide). HRP readily bound to zinc hydroxide but not to aluminum hydroxide in 25.0 mM bicarbonate buffer (pH 9.0). Several variants of HRP polymerization and HRPp modification with diamines in the presence of Al2O3 and Zn(OH)2 were compared. Synthesis of HRPp according to the scheme comprising HRP activation in solution followed by its polymerization in the presence of Zn(OH)2 appeared the most efficient. HRP and HRPp bound to Zn(OH)2 displayed a high catalytic activity in the presence of high H2O2 concentrations.

Adsorption↗

PubMedDate not supplied

[Synthesis and properties of horseradish peroxidase copolymers].

Conditions for copolymerization of native and sodium periodate-oxidized horseradish peroxidase (HTP; EC 1.11.1.7) have been optimized. Copolymerization products have been characterized electrophoretically, spectrally, and kinetically. Copolymers containing 2-3, 4, 5-7, and 9-10 molecules of the enzyme were found among the products of polymerization. The copolymers had lower values of D403/D280 than HRP. The copolymers had more ordered structures than the original HRP. Comparison of the thermal stability and kinetic characteristics of the fractions differing in the ratio of copolymers to the monomeric enzyme demonstrated that the polymeric products were more stable than HRP (in terms of resistance to high temperature or inhibitory effects of H202), but their kinetic activity was, on the whole, lower than that of the original enzyme.

Catalysis↗

PubMedDate not supplied

[Thyroxine-binding globulin and its molecular variant in human amniotic fluid].

Total thyroxine--binding globulin (TBGt) and its pregnancy-associated molecular variant (TBG-1) were detected by radioimmunoassay in human amniotic fluid collected at the time of delivery. TBGt purified from amniotic fluid by affinity chromatography and hydroxylapatite chromatography, displayed electrophoretic properties, immunoreactivity, a molecular mass, affinity for thyroxine and TBG-1 content identical to those of pure TBGt from human pregnancy serum. The concentrations of TBGt and TBG-1 in maternal venous blood serum were 49 +/- 7 mg/ml and 3.8 +/- 1.3 mg/ml (n = 23), respectively, and those in amniotic fluid were 2.0 +/- 0.5 mg/ml and 0.19 +/- 0.12 mg/ml (n = 30), respectively. The analysis of paired samples showed that the serum and amniotic fluid TBGt levels closely correlated (r = 0.91), whereas the correlation between the respective TBG-1 levels was poor (r = 0.63). The TBG-1/TBGt ratio in amniotic fluid was 20% higher than that in serum. These findings suggested a maternal origin of the most of the amniotic fluid TBG which may possibly enter amniotic fluid by passive diffusion through fetal membranes. An alternative mechanism can exist for TBG-1 transfer from maternal serum to amniotic fluid. It corresponds to a special role that TBG-1 may play in the fetoplacental system.

Amniotic Fluid↗