Lipid-protein microdomains in tonoplast of Beta vulgaris L.: comparison between the results obtained by detergent and detergent-free isolation techniques

Abstract

Abstract Objective The membranes of plant and animal cells contain lipid-protein microdomains (LPMs) in their structure. We aimed to compare biochemical and biophysical characteristics of LPMs isolated by the two techniques from beet root tonoplast. Methods For the purposes of comparison the biochemical characteristics of LPMs the content of protein (Bradford’s method), the content of lipids (gravimetric method) were assessed. For the purpose of separating different kinds of lipids, one-dimensional thin layer chromatography (TLC), two-dimensional TLC and different specific systems of solvents were used. The content of fatty acids and sterols was determined by chromatography-mass spectrometry and gas-liquid chromatography-mass spectrometry correspondingly. In order to determine the orderings of the lipids in LPMs the laser scanning confocal fluorescence microscopy was used. Results Significant differences were revealed as a result of investigation of biochemical and biophysical characteristics of LPMs. The total content of proteins was substantially higher (4 times as large) in LPMs identified by the detergent-free technique than in LPMs identified by the detergent technique. The orderings of lipids in LPMs isolated by detergent-free technique was substantially lower than that of LPMs isolated by detergent technique. Conclusion These results may suggest an existence of several types of LPMs in tonoplast.