Steady-state and time-resolved spectroscopic studies on low-density lipoprotein-bound Zn(II)-phthalocyanine
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- 作者：Valduga ; Giuliana ; Pifferi ; Antonio ; Taroni ; Paola ; Valentini ; Gianluca ; Reddi ; Elena ; Cubeddu ; Rinaldo ; et. al.
- 关键词：Zn(II)-phthalocyanine ; Low-density lipoproteins ; Liposomes ; Fluorescence emission
- 刊名：Journal of Photochemistry and Photobiology B: Biology
- 出版年：1999
- 出版时间：April, 1999
- 年：1999
- 卷：49
- 期：2-3
- 页码：198-203
- 全文大小：516 K
文摘
Steady-state and time-resolved spectroscopic studies on Zn(II)-phthalocyanine (ZnPc)-low-density lipoprotein (LDL) complexes obtained through the transfer of ZnPc molecules from dipalmitoyl-phosphatidylcholine (DPPC) or palmitoyl-oleoyl-phosphatidylcholine (POPC)-dioleoyl-phosphatidylserine (OOPS) liposomes have been carried out. The number of ZnPc molecules bound to the LDL particles varies with the liposome type and the ZnPc/LDL concentration ratio in the incubation medium; the ZnPc transfer to LDL is more efficient with POPC-OOPS liposomes. Steady-state fluorescence measurements show a reduction of the ZnPc fluorescence yield as the number of ZnPc molecules bound to LDL increases (about 40 % reduction is observed with a ZnPc/LDL molar ratio of 60 as compared to 1). The fluorescence decay of ZnPc is best fitted by a monoexponential decay with a lifetime of 3.8 ns at a ZnPc/LDL ratio equal to 1, while at higher ratios a shorter-living fluorescence component is detected whose amplitude increases as the ZnPc/LDL ratio is increased. This behaviour suggests the presence of ZnPc aggregates in the LDL particle.