Fluorimetric determination of critical micelle concentration avoiding interference from detergent charge

Dependence of critical micelle concentration of a zwitterionic detergent on ionic strength: implications in receptor solubilization

“…As the amount of CHAPS is increased, the number of micelles increase with a concomitant increase in the amount of bound DPH causing an increase in fluorescence. The CMC is obtained from the intersection of the straight line through the fluorescence at low detergent concentrations with the straight line through the fluorescence values in the region of rapid intensity increase [13]. The CMC of CHAPS determined by this method is 6.41 mM, in the absence of any added salt (see Fig.…”

“…Fluorescence was averaged over 5 s for each sample reading. The protocol for determination of CMC was as follows [13]: 1 pJ of 10 mM DPH dissolved in THF was added to various amounts of CHAPS dissolved in a total volume of 1.5 ml of aqueous solution containing varying concentrations (0-1.5 M) of NaC1. Tubes were vortexed well and incubated in dark for 30 rain at room temperature before measurement of fluorescence.…”

“…Addition of salts is known to drastically decrease the CMC of charged detergents such as SDS [11][12][13] since salt would tend to reduce the repulsion between the charged headgroups, thereby helping the micelles to be formed at lower concentra-*Corresponding author. Fax: (91) 40-671195.…”

Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels

“…Thus, we may determine how readily the dansyl group fluorescence is quenched in the presence of nitroxides placed at different distances from the midplane of the bilayer. By so doing, one may triangulate the distance of the dansyl residue from the bilayer midplane [60]. Such studies conducted with 13 indicated that the dansyl residues are located 14 Å from the bilayer midplane [61].…”

Interaction of Serotonin1AReceptors from Bovine Hippocampus with Tertiary Amine Local Anesthetics

“…Background intensities of samples in which fluorophores were omitted were negligible and were subtracted from sample intensities to cancel out any scattering artifacts. To reverse any photoisomerization of DPH, samples were kept in dark in the fluorimeter for 30 s before the excitation shutter was opened and fluorescence was measured (Chattopadhyay and London, 1984). Fluorescence polarization measurements were performed at 23 • C using a Hitachi polarization accessory.…”