These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Time-resolved fluorescence anisotropy of fluorescent-labeled lysophospholipid and taurodeoxycholate aggregates.
    Author: DeLong LJ, Nichols JW.
    Journal: Biophys J; 1996 Mar; 70(3):1466-71. PubMed ID: 8785303.
    Abstract:
    Previous work from this laboratory demonstrated that the environment-sensitive lysolipid N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)- monomyristoylphosphatidylethanolamine (N-NBD-MPE), at concentrations below its critical micelle concentration (CMCN-NBD-MPE = 4 microM), reached maximum fluorescence yield upon the addition of taurodeoxycholate (TDC) at concentrations well below its CMC (CMCTDC = 2.5 mM). These data indicated the formation of micellar aggregates of the two amphiphiles at concentrations below both of their CMCs. In the present study, fluorescence lifetime and differential polarization measurements were made to determine the size of these aggregates. In the absence of TDC and at 0.5 mM TDC a single lifetime (tau) and rotational correlation time (phi) were measured for N-NBD-MPE at the submicellar concentration of 2 microM, indicating a lack of interaction between the two molecules at this concentration. Above 0.5 mM TDC, two discrete lifetimes were resolved. Based on these lifetimes, two distinct rotational correlation times were established through polarization measurements. The shorter phi(0.19-0.73 ns) was ascribed to local probe motions, whereas the longer phi was in a time range expected for global rotation of aggregates the size of simple bile salt micelles (3-6.5 ns). From the longer phi, molecular volume and hydrodynamic radii were calculated, ranging from approximately 15 A at 1 mM to approximately 18 A at 5 mM TDC. These data support the conclusion that monomeric lysolipids in solution seed the aggregation of numerous TDC molecules (aggregation number = 16 at 1 mM TDC) to form a TDC micelle with a lysolipid core at concentrations below which they both self-aggregate.
    [Abstract] [Full Text] [Related] [New Search]