Limited rotational motion of amphiphilic flavins in dipalmitoylphosphatidylcholine vesicles |
| |
Authors: | AJWG Visser |
| |
Institution: | Department of Biochemistry, Agricultural University, De Dreijen 11, 6703 BC Wageningen The Netherlands |
| |
Abstract: | The rotational motion of amphiphilic flavins in dipalmitoyl phospholipid bilayers was investigated with fluorescence anisotropy decay measurements. At temperatures between 10 and 50°C the rotation proved to be anisotropic, which indicated composite motion of both the aliphatic side-chain and the isoalloxazine moiety of the octadecyllumiflavin derivatives. Above the phase transition temperature (crystalline→liquid-crystalline state) the depolarization is complete within the average flavin fluorescence lifetime, implicating unrestricted motion and resulting in a non-ordered microenvironment. In the gel or crystalline state the flavin motion can best be characterized as a limited rotation or librational motion. The fluorescence decay of the flavins is heterogeneous at temperatures between 10 and 50°C, which is explained by assuming nanosecond relaxation of the polar phosphatidyl head-groups around the excited flavin. The lack of a significant cholesterol effect suggests that the isoalloxazine is located at the interphase of the bilayer and not in the hydrocarbon region. The microstructure is fluid-like, not in agreement with a preferred static localization of the flavins in the bilayer. |
| |
Keywords: | Anisotropy decay Fluorescence decay Order parameter Dipalmitoylphosphatidylcholine vesicle Amphiphilic flavin Vesicle DPH 1 6-diphenyl-1 3 5-hexatriene OLF octadecyllumiflavin DPPC dipalmitoylphosphatidylcholine |
本文献已被 ScienceDirect 等数据库收录! |