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Electric field‐induced conformational change of poly( L ‐lysine) studied by transient electric birefringence
Author(s) -
Kikuchi Kazuo,
Yoshioka Koshiro
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360150904
Subject(s) - birefringence , electric field , chemistry , field strength , flow birefringence , helix (gastropod) , methanol , solvent , analytical chemistry (journal) , optics , polymer , chromatography , magnetic field , organic chemistry , physics , ecology , quantum mechanics , snail , biology
Transient electric birefringence measurements on poly( L ‐lysine hydrobromide) in methanol–water mixtures have been carried out at various solvent compositions in the vicinity of the helix–coil transition region (from 87 to 98 vol % methanol). Anomalous birefringence transients were observed between 90 and 95 vol % methanol above a threshold field strength. A distinct difference between the responses to weak and strong electric fields was noticed over a narrow range of the solvent composition. The effects of polymer concentration and temperature on the field‐strength dependence of the birefringence were studied at a solvent composition of 90 vol % methanol where the anomalous transients appeared most clearly. The double logarithmic plots of the steady‐state specific birefringence versus the square of field strength for different concentrations and temperatures could be superimposed by shifting them horizontally along the abscissa. The threshold field strength which was determined from the shift factor decreased with decreasing concentration. The results provide further evidence that strong electric fields can cause a helix–coil transition in this system under favorable conditions.