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THE USE OF NEUTRAL RED TO MONITOR THE SURFACE POTENTIAL OF THE PURPLE MEMBRANE
Author(s) -
LI QINGGUO,
NI YAJUN,
CAO YI
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb08493.x
Subject(s) - chemistry , neutral red , titration , salt (chemistry) , membrane , membrane potential , analytical chemistry (journal) , ionic bonding , chromatography , inorganic chemistry , ion , biochemistry , organic chemistry , cytotoxicity , in vitro
— The binding of neutral red to purple membrane has been studied. The intrinsic p K a and the apparent p K a , of bound neutral red were determined by titration and by measuring the binding ratio of neutral red to purple membrane as a function of pH. The surface potential of purple membrane was inferred from the difference between these two p K a s. The H + /M412 ratio at different ionic strengths was also measured and compared with the surface potential. The results show that the H + /M412 decreased as the surface potential increased due to decreased salt concentrations. However, this correlation holds only for KCl concentrations higher than 30 m M . At lower salt concentrations, the change in surface potential is always less than the variation in the H + /M412 ratio.