Search PubMed⌕ Search

Biomedical subjects

C Balny

Publications and source records attributed to C Balny.

At least 91 records · Page 5Linked to original sources
PubMed1979

New trends in cryoenzymology : II. - Aqueous solutions of enzymes in apolar solvents.

In order to set up new procedures to investigate enzyme systems at subzero temperatures in pure aqueous media, we used micromicellar solutions which are homogeneous, optically transparent and of low viscosity in that range of temperatures. The preparation and the main properties of such solutions are described along with the behavior of enzyme-substrate intermediates. A critical discussion of results permits to examine advantages as well as limitations of this very promising procedure.

Blood Proteins↗
PubMed1979

Cryoenzymology in aqueous media: Micellar solubilized water clusters.

Amphiphilic compounds dissolved in nonpolar organic solvents form inverted micelles whose aqueous centers can solubilize relatively large amounts of enzymes. The solutions are homogeneous and optically transparent and have low viscosity and freezing points; they provide unique and favorable systems to perform the main cryoenzymologic studies previously carried out in mixed solvents. The preparation and properties of such micelles are described. The absorbance spectra of cytochrome c at various temperatures from -38 degrees C to 20 degrees C are given. The pH dependence of trypsin-catalyzed hydrolysis of benzoylarginine ethyl ester in inverted micelles, as well as kinetic properties and activation energy, is described. Some problems are analyzed.

Journal Article↗
PubMed1978

Organic solvents and temperature effects on desorption from immunoadsorbents. DNP-BSA anti-DNP as a model.

Conditions for desorbing a DNP carrier from its immunoadsorbent were studied in various hydro-organic media at different pHs and temperatures, including the sub-zero range. It appeared that DNP--anti-DNP interaction is the result of a balance between various bonds and the best result (95% yield) was obtained in hydro-organic solvent at high pH and +30 degrees C.

Antigen-Antibody Complex↗
PubMed1978

New trends in cryoenzymology: I.-Supercooled aqueous solutions.

A water in oil emulsion technique is proposed to investigate enzyme catalyzed reactions at sub-zero temperatures in the supercooled liquid state to avoid some reversible effects of the usual cosolvents on kinetics. Some results are listed: potentialities and technical problems of the procedure are discussed.

Alcaligenes↗
PubMed1978

Biochemical effects on radioprotective agents on the liver microsomal hydroxylating system: in vitro studies.

The action of two radioprotectors--cysteamine and cystamine--on the liver microsomal multi-enzyme hydroxylating system, a key stem in drug and biological compounds metabolism, has been studied. Their effects have been systematically analysed at the level of individual enzyme activities and global functions. The two compounds are quite inactive on NADPH and NADH cytochrome c reductase activities, but slightly denature the cytochrome P450 into cytochrome P420. Furthermore, they do inhibit to some extent (30 per cent at 10(-2) M) the rate of codeine hydroxylation and totally suppress ((at 10(-2) M) the NADPH-induced lipid peroxidation which occurs during enzymatic functioning. These results are discussed in the light of the toxicity of radioprotectors.

Animals↗
PubMed1977

Cryoenzymology in mixed solvents without cosolvent effects on enzyme specific activity.

Water-soluble polyelectrolytes in interaction with proteins are described. These polyelectrolytes make it possible to investigate enzyme-catalyzed reactions in cooled mixed solvents without the usual effects of their organic solvent component on enzyme specific activity. The applicability of techniques developed is illustrated by results obtained on several systems. The possibility of an electrostatic "sorting out" of solvents and its potentialities in cryoenzymology are discussed.

Cold Temperature↗
PubMed1975

Fluorescence and bioluminescence of bacterial luciferase intermediates.

An intermediate in the luciferase-catalyzed bioluminescent oxidation of FMNH2, isolated and purified by chromatography at -20degrees, was postulated to be an oxygenated reduced flavin-luciferase. Maintained and studied at -20 to -30degrees, this material exhibits a relatively weak fluorescence emission peaking about 505 nm when excited at 370 nm. It may comprise more than one species. Upon continued exposure to light at 370 nm, the intensity of this fluorescence increases, often by a factor of 5 or more, and its emission spectrum is blue shifted to a maximum at about 485 nm. Upon warming its fluorescence is lost and the fluorescence of flaving mononucleotide appears. If warming is carried out in the presence of a long chain aldehyde, bioluminescence occurs, with the appearance of a similar amount of flavine fluorescence. The bioluminescence yield is about the same with irradiated and nonirradiated samples. The bioluminescence emission spectrum corresponds exactly to the fluorescence emission spectrum of the intermediate formed by irradiation, implicating the latter as being structurally close to the emitting species in bioluminescence.

Flavin Mononucleotide↗
PubMed1975

The oxygenated bacterial luciferase-flavin intermediate. Reaction products via the light and dark pathways.

The identity and stoichiometry of the reaction products of the oxygenated reduced flavin bacterial luciferase intermediate isolated by Sephadex chromatography at low temperature have been determined under two conditions, allowing the reaction to go to completion by warming either in the presence or absence of long chain aliphatic aldehyde. In the latter case, very little bioluminescence occurs, and 1 mol each of H2O2 and FMN is produced per mol of enzyme intermediate. In the presence of aldehyde, the formation of an aldehyde-enzyme intermediate complex can be detected by optical absorption spectroscopy at -30 degrees; upon warming, bioluminescence with high quantum yield occurs with the formation of 1 mol of FMN but no H2O2.

Darkness↗
PubMed1975

Recombination of carbon monoxide with hemoglobin after flash photolysis of the carboxyderivative in mixed solvents at subzero temperature.

The kinetics of recombination of carbon monoxide to hemoglobin produced by total flash photolysis of its carboxyderivative are studied at low temperatures (down to --55 degrees C) in mixed hydroalcoholic solvents. The rates are found to be different in two solvents used, namely ethylene glycol/buffer and methanol/buffer; for the former, the rates at subzero temperatures are simply explained by cooling and are consistent with the activation energy as measured in aqueous solution, while those in methanol/buffer show evidence of a specific solvent effect. Values are reported for the rate constants and activation energies in the two solvents.

Carbon Monoxide↗