Site-specific modification or rabbit muscle aldolase with fluorescent probes.

The site-specific modification of rabbit muscle aldolase A by labeling of thiol residues of Cys-289 with 5-(2-((iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid and Cys-239 with 5-iodoacetamidofluorescein or 4-dimethylamino-phenylazophenyl-4'-maleimide has been described. The method is based on the differences in kinetics of the chemical modification of aldolase thiols with the above reagents either in the presence or in the absence of a competitive inhibitor. The spectral properties of the doubly labeled aldolase derivatives were compared with those of the singly labeled enzyme.

Theoretical investigations on the structure and potential binding sites of antineoplaston A10 and experimental findings.

The essential biological importance of antineoplastons has motivated the present theoretical and experimental studies on the structure and potential binding sites of Antineoplaston A10, 3-phenylacetylamino-2,6-piperidinedione. Semi-empirical molecular orbital calculations SCF-LCAO-MO were performed using the MNDO method. The calculated molecular geometry of A10 is in very good agreement with the recently obtained X-ray structure of synthetic A10.

Uranium and lead accumulation in cells of Streptomyces sp.

Lead and uranium were accumulated equally well both in the viable and dry biomass of Streptomyces sp. The process occurred in less than 5 min. Uranium was accumulated selectively from a polymetallic solution containing U, Pb, Cu, Zn, Ni, Co.

Ultrafiltration membranes as carriers for lipase immobilization.

The feasibility of directly incorporating lipase from Rhizopus in the interior of poly(vinyl chloride) ultrafiltration membranes during the phase inversion process for their manufacturing has been demonstrated. The obtained membranes used for plant oil hydrolysis have shown better time stability as compared with those of lipase immobilized by adsorption. The specific activity of entrapped lipase achieves values higher than those of the soluble one.

The interaction of fructose-1,6-biphosphate aldolase with liposome membranes: a spin probe technique study.

Thermotropic properties of liposome membranes prepared of bulk bovine erythrocyte membrane lipids, native, or aldolase-modified, were investigated by the ESR method. Breaks were observed in the log 2T parallel vs 1/T plots for two spin labels: tempopalmitate and 5-doxyl-palmitate methyl ester. These phenomena have been interpreted as reflecting structural changes near the lipid bilayer polar heads region.

Removal of RNA during protein concentration by means of enzyme membrane.

Immobilization of RNase in PVC ultrafiltration membranes was carried out. The obtained membranes were used for concentration of BSA solution, RNA being simultaneously removed. The yield of RNA hydrolysis was found to be controlled by the initial concentration of RNA in feed solution.

Voltammetric behaviour of the chromium(III)-5-sulphosalicylate complex.

Voltammetric studies have been made of solutions containing the chromium(III)-5-sulphosalicylate complex (CrL) in the presence of 5-sulphosalicylic acid and 0.5M sodium perchlorate. The electrochemical behaviour of the chromium complex indicates that an adsorption-electroreduction process predominates at higher concentrations of CrL, which is important from a practical point of view.

Contribution of SO2 sorption on particulate surface to the air pollution level in the vicinity of coal-fired power plants.

The area under study is influenced by three lignite-fired power plants. The distribution of SO2 concentrations in the air over the area has been calculated. The calculations include SO2 sorption on the surface area of the emitted particulates--stack dust and fly ash.

Inhibition of aminopeptidases by aminophosphonates.

More than 30 aminophosphonates were synthesized to probe how the structural changes introduced into the phosphonic acid analogue of leucine, a potent inhibitor of cytosolic leucine aminopeptidase (Giannousis & Bartlett, 1987), affect their ability to inhibit cytosolic (EC 3.4.11.

Effect of DIDS on osmotic properties of bovine erythrocytes.

The effect of DIDS on osmotic properties of bovine erythrocytes was studied. The isoosmotic volume, the amount of intracellular solutes, and the osmotically non-active volume were not influenced by DIDS. An increase of osmotic fragility of erythrocytes upon DIDS treatment was evident and identical both in NaCl and in NaCl + KCl hypotonic solutions.

Fluorescence resonance energy transfer studies on the proximity between lysine-107 and cysteine-239 in rabbit muscle aldolase.

Spatial relationships between Lys-107, which binds the C-6 phosphate group of the substrate, and fast-reacting Cys-239, located outside the active site of rabbit muscle aldolase, were studied by means of resonance energy transfer. The Lys-107 residue was covalently linked to pyridoxal phosphate (fluorescence donor) and the Cys-239 residue was modified by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (fluorescence acceptor). The energy transfer between donor and acceptor has been demonstrated.

Osmotic properties of bovine erythrocytes aged in vivo.

The osmotic properties of bovine erythrocytes aged in vivo were studied by the modified microhematocrit method. The osmotic fragility of older red cells decreases due to their larger relative osmotically non-active volume. Relative critical cell volume of bovine erythrocytes does not alter significantly with cell age.

Photoaffinity labeling of rabbit muscle fructose-1,6-bisphosphate aldolase with 8-azido-1,N6-ethenoadenosine 5'-triphosphate.

Steady-state kinetic measurements have shown that 8-azido-1,N6-ethenoadenosine 5'-triphosphate (8-N3-epsilon ATP) can be noncovalently bound to rabbit muscle fructose 1,6-bisphosphate aldolase with Ki = 0.075 mM at pH 8.5.

Reversible denaturation with urea of rabbit liver fructose-1,6-bisphosphatase.

Denaturation of fructose-1,6-bisphosphatase (Fru-P2-ase, EC 3.1.3.

Determination of uranium in phosphogypsum.

A method for determination of uranium in phosphogypsum is based on extraction of uranium from phosphoric acid in which hydration transformations of calcium sulphate hydrates have occurred. The uranium is extracted with a kerosene solution of a mixture of mono- and dinonylphenylphosphoric acids, then stripped with concentrated phosphoric acid, and determined spectrophotometrically with Arsenazo III.

Determination of uranium in wet phosphoric acid.

A method for quantitative determination of uranium in wet phosphoric acid containing 0.001-0.02% of uranium has been developed.

Continuous transformation of benzaldehyde to benzyl alcohol by Rhodotorula mucilaginosa immobilized in an ultrafiltration cell.

Microbiological transformation of benzaldehyde accomplished by the fungus Rhodotorula mucilaginosa immobilized in the ultrafiltration cell was studied. A polysulfone membrane formed on a sintered PVC support was used for the separation of the transformation product from the cellular material. Kinetic investigations have led to results which are typical of continuously fed stirred tank reactors (CFSTR)-the value of the maximum reaction rate (V(max)) and apparent Michaelis constant (K'(m)) are practically independent of the substrate retention time (calculated in terms of the flow intensity value).

Differentiation of a noninteger order and its optical implementation.

This paper gives the definition and examples of an arbitrary order differentiation based on some properties of the Fourier transform. To physically implement the generalized differentiation a coherent processing system with binary synthetic filter was used. The experimental part of the paper shows models of the 1-D and 2-D binary filters and results of the filtering process.