ESR investigation of the structural transition of spectrin in ghosts and in solution

The effect of temperature on the human erythrocyte ghosts and on isolated spectrin, both labelled with a protein spin label (2, 2, 6, 6 tetramethylpiperidin - 1 - oxyl - 4 - maleimide), was studied by the electron spin resonance spin label method. The results show that the spectra associated with the membrane undergo significant changes with temperature and a well-defined transition is detected at 52 degrees C. The observed transition is removed from the membrane by the extraction of spectrin and in the supernatant the transition is unchanged from that exhibited by the native ghosts. The results show that it is possible to observe the heat dependent transition of the spectrin in whole ghosts avoiding the extraction procedure.