QUENCHING OF TRYPTOPHAN FLUORESCENCE BY BROMINATED PHOSPHOLIPID

被引:159
作者
BOLEN, EJ [1 ]
HOLLOWAY, PW [1 ]
机构
[1] UNIV VIRGINIA,SCH MED,DEPT BIOCHEM,CHARLOTTESVILLE,VA 22908
关键词
D O I
10.1021/bi00493a019
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
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 Å. 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. © 1990, American Chemical Society. All rights reserved.
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页码:9638 / 9643
页数:6
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