Comparison of Binding Ability and Location of Two Mesoporphyrin Derivatives in Liposomes Explored with Conventional and Site-Selective Fluorescence Spectroscopy

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• 作者：D谩niel Veres ; Barnab谩s B艖cskei-Antal ; Istv谩n Voszka ; K谩roly M贸dos ; Gabriella Cs铆k ; Andr谩s D. Kaposi ; Judit Fidy ; Levente Herenyi
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：August 16, 2012
• 年：2012
• 卷：116
• 期：32
• 页码：9644-9652
• 全文大小：437K
• 年卷期：v.116,no.32(August 16, 2012)
• ISSN：1520-5207

文摘

Application of porphyrins as photosensitizers is based on their light-triggered generation of reactive oxygen species (ROS) that may cause oxidative tissue damage and ultimately kill cells. Cellular membranes are the action grounds of many sensitizers due to their hydrophobic or amphiphilic character as well as the location of many of the targets attacked by ROS. Hence, the binding ability and location of porphyrins in liposomes as simple models of cellular membranes are of outstanding interest. Here we compare mesoporphyrin IX dimethyl ester (MPE) and its nonesterified form, mesoporphyrin IX dihydrochloride (MPCl). Monocomponent small unilamellar vesicles formed of various saturated phosphatidylcholines with incorporated mesoporphyrins were investigated. We determined the binding parameters and the inhomogeneous distribution functions (IDFs) by different fluorescence techniques. We found in general that the binding ability of MPE is considerably greater than that of MPCl. In the case of MPCl, the IDFs suggest that only one of the two binding site types identified earlier for MPE (鈥渟ite II鈥? exists; the other one (鈥渟ite I鈥? vanishes while a new one appears (鈥渟ite III鈥?. We can confirm that 鈥渟ite I鈥?is located between the two lipid layers, 鈥渟ite II鈥?is situated between the hydrocarbon chains, while the location of the novel 鈥渟ite III鈥?is along the outer part of the hydrocarbon chains partially inserted between the lipid head groups.