title: Differences in the electric birefringence of spectrin dimers and tetramers as shown by the fast reversing electric pulse method.
abstract: The electric birefringence of purified spectrin has been examined in medium of low ionic strength at 20 degrees C and for electric fields smaller than 4 X 10(4) V m(-1), using the reversing electric pulse method. This technique allows study of the permanent and induced dipole electric moment of macromolecules more easily than in measurements using only rectangular pulses. We show that spectrin heterodimers and heterotetramers have different electro-optical properties. The relaxation time of the tetramer (7 microseconds) is significantly longer than that of the dimer (4.5 microseconds). Tetramers and dimers have also different polarizability parameters.
mesh_terms: D001718:Birefringence; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D008565:Membrane Proteins / Q000302:isolation & purification; D013049:Spectrin / Q000302:isolation & purification
chemical_list: D046911:Macromolecular Substances; D008565:Membrane Proteins; D013049:Spectrin