On the use of a piperidine maleimide spin label to investigate membrane proteins in erythrocyte membranes with reference to Huntington's disease

The spin label 2,2,6,6-tetramethyl-4-maleimidopiperidine-1-oxyl, when reacted with erythrocyte ghosts is specific for and covalently bound to membrane proteins. While this spin probe has been previously used to monitor the effects of various agents and procedures on the physical state of membrane proteins and to assess differences in conformation and/or organization of membrane proteins in pathologic conditions, no systematic investigation has been undertaken to determine the biochemical parameters that can affect the resulting electron spin resonance spectra. The present study reports the effects of several conditions that must be monitored if meaningful conclusions are to be drawn from spin-label investigations using this protein-specific nitroxide. The results are discussed with reference to spin labeling studies in Huntington's disease.