We have presented the effects of several chemical modification procedures on the properties of excitable membranes. The approach represents a middle ground between the biochemical approach of total separation of the proteins responsible for excitability and the biophysical approach in which only the physical parameters associated with the proteins are described. The results from investigations using group specific probes have begun to provide some picture, albeit a sketchy one, of the functional architecture of the proteins associated with excitability. As such, the investigations provide important information about necessary residues and their conformational arrangement in the intact protein. This knowledge will be especially useful in understanding excitability once the primary amino acid structure of the excitability proteins is determined.