A Study on the Motion Of Protenis in Excitable Membrane Fragment by Nanosecond Fluorescence Polarization Spectroscopy

Abstract

The motion of two fluorescent dyes, 1‐anilino‐8‐naphthalene sulphonate, which binds reversibly, and 5‐dimethylamino‐1‐naphthalene sulphonyl chloride, which binds covalently to excitable membrane fragments in vitro , has been studied by nanosecond fluorescence polarization spectroscopy. Both dyes were strongly immobilized by their association wtih membrane proteins. Solubilization by Triton X‐100 of an important fractioon (60%) of the proteins from membrane fragments heavily labelled with 5‐dimethylamino‐1‐naphthalene sulphonyl chloride was accompanied by a dramatic increase of motion. It is concluded that proteins are strongly immobilized within the membrane phase.