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R C YashRoy

Publications and source records attributed to R C YashRoy.

9 recordsLinked to original sources
PubMed1994

Destabilisation of lamellar dispersion of thylakoid membrane lipids by sucrose.

Employing negative-staining electron microscopy, convincing evidence has been obtained for the destabilisation of multilamellar organisation of aqueous dispersions of chloroplast thylakoid membrane lipids, to an inverted micellar structure under the influence of sucrose solution. The present study provides a new insight into the phase behaviour of a naturally existing galactolipid-rich lipid mixture consequent to interaction with a kosmotropic reagent.

Chloroplasts↗
PubMed1991

Protein heat denaturation and study of membrane lipid-protein interactions by spin label ESR.

Spinach chloroplast membranes labelled with stearic acid-spin probe-bearing nitroxyl (label) moiety at 5th, 9th, 12th, 13th, 14th or 16th carbon locations with respect to the carboxylic group of stearic acid were studied (in the dark) by electron spin resonance (ESR) spectroscopy. Spectra were recorded at sample temperatures of 5, 30 and 67 degrees C. After heat denaturation of the membrane proteins for 5 min at 67 degrees C, the spectra were re-recorded at 30 and 5 degrees C for comparison. The results unequivocally show that membrane lipid fatty-acyl chains become substantially more rigid after protein heat-denaturation. The data throw light on the degree of lipid-protein interactions at various microlocations along the length of fatty-acyl chains of the membrane lipid matrix.

Chloroplasts↗
PubMed1987

Carbon-13 NMR studies of chloroplast membranes: carbon-13 enrichment without 13C-13C couplings.

A novel approach to carbon-13 (13C) enrichment of chloroplast membranes (and plant materials in general) is presented for 13C-nuclear magnetic resonance (13C-NMR) studies. The method minimizes the occurrence of spectral complications arising from 13C-13C couplings resulting from a statistical distribution of 13C within the molecule with low probability of encountering two 13C atoms adjacent to each other. This is achieved by growing the plants in light surrounded by an atmosphere containing 1/3rd 12CO2 and 2/3rd 13CO2, liberated by weak acid-treatment of a mixture of corresponding barium carbonate salts.

Carbon Isotopes↗
PubMedDate not supplied

Determination of membrane lipid phase transition temperature from 13C-NMR intensities.

A new and simple approach for the determination of the temperature of gel-to-liquid crystalline phase transitions (Tc) of biological (chloroplast) membrane lipids from 13C-NMR resonance intensities is proposed. The variation of intensity of a temperature-sensitive NMR resonance is monitored by recording the spectra of the sample at a range of temperatures. From such a series of spectra recorded at different temperatures, a temperature-insensitive resonance is located. Then the ratio of the intensity of the temperature-sensitive to the intensity of the temperature-insensitive resonance is calculated from each spectrum to even out the procedural error, if any. The values of this ratio at different temperatures, when plotted against sample temperature, shows a break at Tc as confirmed by spin label ESR studies.

Chemical Phenomena↗
PubMedDate not supplied

13C-NMR studies of membrane lipid-protein interactions upon protein heat denaturation.

Spinach chloroplast membranes were studied by natural abundance carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy in their normal state and after heat denaturation of membrane proteins. The membrane proteins were denatured by raising the temperature of the sample to 67 degrees C for 5 minutes [YashRoy, R.C. (1991) J. Biochem. Biophys. Methods 22, 55-59]. Line-broadening of 13C-NMR resonances arising from the 1st (carbonyl), 7th, 9th and 12th carbon atom of fatty-acyl chains with reference to the carbonyl (C-1) group shows increased immobilization of lipid fatty-acyl chains at these locations, obviously caused by changes in interactions between membrane lipids and proteins upon heat denaturation of membrane proteins.

Carbon Isotopes↗