Quenching of tryptophan fluorescence by brominated phospholipid

Biochemistry. 1990 Oct 16;29(41):9638-43. doi: 10.1021/bi00493a019.


Bromolipids [1-palmitoyl-2-(dibromostearoyl)phosphatidylcholine] with bromines at the 4,5-, 6,7-, 9,10-, 11,12-, and 15,16-positions were used to examine the fluorescence quenching of a synthetic, membrane-spanning peptide (Lys2-Gly-Leu8-Trp-Leu8-Lys-Ala-amide) incorporated into both small and large unilamellar vesicles. The peptide-lipid vesicles were analyzed to show that at least 75% of the peptide was in a transbilayer configuration, placing the single tryptophan in its predicted place in the center of the bilayer. Quenching profiles of the peptide in bromolipid showed maximal (90%) quenching by the 15,16-bromolipid, indicating that the bromolipids can accurately locate the position of a tryptophan in the bilayer. The quenching by the other bromolipids decreased with an r6 dependence and an apparent R0 of 9 A. In addition, indole in methanolic solution was subjected to quenching by a variety of mono- and dibrominated hydrocarbons. The quenching was analyzed, by using a modified Stern-Volmer equation, and found to be greatly dependent upon the number and positioning of the bromines. Monobromobutanes were found to have a quenching efficiency of only 7% while dibromobutanes, with bromines on adjacent carbon atoms, had efficiencies of over 80%. In addition, the dibromobutanes exhibited significant "static" quenching whereas the monobrominated butanes did not. These data suggest that the bromolipids are more appropriately defined as short-range quenchers rather than strictly contact quenchers.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Kinetics
  • Lipid Bilayers*
  • Molecular Sequence Data
  • Oligopeptides / chemical synthesis
  • Oligopeptides / chemistry*
  • Phosphatidylcholines*
  • Protein Conformation
  • Spectrometry, Fluorescence / methods
  • Tryptophan*


  • Lipid Bilayers
  • Oligopeptides
  • Phosphatidylcholines
  • Tryptophan