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Biomedical subjects

C Balny

Publications and source records attributed to C Balny.

108 records · Page 6Linked to original sources
PubMed1973

Spectral properties of an oxygenated luciferase-flavin intermediate isolated by low-temperature chromatography.

Bacterial luciferase catalyzes the oxidation of reduced flavin mononucleotide by molecular oxygen; long-chain aldehyde is required for light emission. At 20 degrees the bioluminescence has a lifetime of tens of seconds, while excess reduced flavin is removed by way of nonenzymatic autoxidation in less than a second. This observation indicates the existence of a long-lived enzyme intermediate, which has been postulated to be a peroxide of the enzyme-bound reduced flavin. This intermediate was isolated and studied at low temperature (-20 degrees ), where it has a lifetime measured in days. It has an absorption with a single band peaking at 372 nm, and fluorescence emission centered at about 485 nm, which might be expected for the postulated flavin peroxide. Upon conversion to product, flavin mononucleotide-like absorption and fluorescence appear, supporting the postulate that flavin turns over in the reaction. Upon injection into buffer at 20 degrees with added aldehyde, bioluminescence occurs. Based on a stoichiometry of one flavin per luciferase molecule, the specific activity of the intermediate is equal to that of pure luciferase.

Journal Article↗
PubMed1973

Enzyme assay in microsomes below zero degrees.

Reactions of a membrane-bound multienzyme complex (electron-transport chain of rat-liver microsomes) suspended in aqueous-organic solvent used as antifreeze at temperatures below 0 degrees were studied. In the presence of a relatively high concentration of ethylene glycol, electron transfer can still be observed and some individual and sequential enzyme assays can be performed over a wide range of temperatures below 0 degrees .

Animals↗
PubMedDate not supplied

A stopped-flow study of the reaction of reduced cytochrome oxidase with oxygen.

The reaction of a reduced cytochrome oxidase system consisting of beef heart cytochrome oxidase, cytochrome c, and ascorbate with molecular oxygen was kinetically and thermodynamically investigated using a stopped-flow, rapid wavelength-scanning technique. Processes for oxidation of ferrocytochrome a, bound ferrocytochrome c, and free ferrocytochrome c have been identified, and their rate constants have been determined. Values of the activation energy for these reactions indicate that the oxidation of bound ferrocytochrome c is a simple chemical electron-transfer process and that oxidations of ferrocytochrome a and free ferrocytochrome c are complex processes involving changes in protein conformation.

Animals↗