diamide and maleimide

Using EPR technique we have examined the effect of chemical agents on pig erythrocyte membranes. Treatment of the erythrocyte membranes with SH-oxidizing and denaturing or specific for amino groups reagents affects both the membrane proteins and lipids. These results suggest that modified proteins may perturb the interactions of the membrane components and lead to alterations of the membrane organization in the polar region.

Topics: Animals; Diamide; Dimethyl Suberimidate; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane; Maleimides; Membrane Fluidity; Membrane Proteins; Spin Labels; Swine; Urea

The release of hemoglobin from human erythrocytes hemolyzed beforehand by hydrostatic pressure, osmotic pressure, and freeze-thaw methods was examined as a function of temperature (0-45 degrees C) and pH (5.5-8.8) at atmospheric pressure. Only in the case of high pressure (2,000 bar) did the release of hemoglobin increase significantly with decreasing temperature and pH. Maleimide spin label studies showed that the temperature and pH dependences of hemoglobin release were qualitatively explicable in terms of those of the conformational changes of membrane proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of membrane proteins showed the diminution of band intensities corresponding to spectrin, ankyrin, and actin in the erythrocytes hemolyzed by high pressure. Cross-linking of cytoskeletal proteins by diamide stabilized the membrane structure against high pressure and suppressed hemoglobin release. These results indicate that the disruption of cytoskeletal apparatus by high pressure makes the membrane more leaky.

Topics: Cross-Linking Reagents; Cytoskeleton; Diamide; Electron Spin Resonance Spectroscopy; Electrophoresis, Polyacrylamide Gel; Erythrocyte Membrane; Erythrocytes; Freezing; Hemoglobins; Hemolysis; Humans; Hydrogen-Ion Concentration; Hydrostatic Pressure; Maleimides; Membrane Proteins; Osmotic Pressure; Pressure; Spin Labels; Temperature