Fluorescence with sodium cholate

The alkylphosphonic acids, MPA, EPA, and PPA, have been determined by direct fluorescence after derivatization with 4-(9-anthroxyloxy)phenacyl bromide (panacyl bromide) (18). The 325-nm line of the HeCd laser was used for excitation. The neutral derivatives required MEKC for the separation and 50 mM sodium cholate was used as the pseudo-stationary phase. Separation was achieved in 33 min and limits of detection ranged from 0.13-0.14 xM (12-17ppb). 

FIGURE50.9 Electrokinetic stacking injection on a microchip. Sample 67 nM BODIPY (a neutral fluorescent dye) in 150 mM NaCl. Run bnffer 80 mM sodium cholate, 10% ethanol, 5 mM tetraborate, pH 9. Sample was first injected by applying an electric field of 183 V/cm between the sample reservoir (S) and the outlet (O) for various periods of time as indicated in the figure. Separation was then carried out by applying 366 V/cm between the inlet (I) and outlet (O). An 80-s injection of 134 nM BODIPY in run buffer is included to show nonstacking injection. (From Palmer et al., Anal. Chem., 73, 725, 2001. With permission.)... 

Burman et al. (2014) studied the interaction of a variety of anionic surfactants including sodium dodecyl sulfate (SDS), sodium cholate (NaC), sodium deoxycholate (NaDC), and sodium taurode-oxycholate (NaTDC) with a nonionic polymer of hydroxy propyl cellulose (HPC). They applied the microcalorimetric, conductometric, and fluorimetric methods to study the interactions. Using calorimetric and conductometric techniques, they could obtain some of the solution properties such as the critical aggregation concentration (CAC), critical micelle concentration (CMC), polymer saturation concentration (PSP), and the extent of binding of the surfactants with polymer. They concluded that the hydrophobicity and charge density of surfactant have a strong effect on micelliza-tion. The fluorescence results showed that increasing the surfactant concentration decreased the micro-polarity. 

Further characterization of this lipid-protein aggregate by Sklan et al. (1982) indicated that it was composed of approximately equal parts of protein and of lipid (mainly triglycerides) and contained approximately 19% of the total liver vitamin A (predominantly as retinyl esters). Much of the liver CRBP and of the RPH activity present in the cytosol was also found associated with the fluorescent lipid-protein aggregate. The lipid-protein aggregate and its several retinol-related components displayed an apparent hydrated density between 1.052 and 1.090 in the ultracentrifuge. Three other lipid hydrolytic activities were also found in association with the lipid-protein aggregate, namely, triolein, cho-lesteryl oleate, and phosphatidylcholine hydrolase activities. These several hydrolytic activities were all found to be stimulated optimally by the addition of either sodium cholate or bovine serum albumin. 

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