Ricchelli F, Gobbo S, Moreno G, Salet C, Brancaleon L, Mazzini A
Consiglio Nazionale delle Ricerche, Centro Metalloproteine, Dipartimento di Biologia, Università di Padova, Italy.
Eur J Biochem. 1998 May 1;253(3):760-5. doi: 10.1046/j.1432-1327.1998.2530760.x.
This paper describes studies of some photophysical properties of non-covalent planar aggregates of hematoporphyrin and protoporphyrin. This porphyrin species has been recently discovered and can be generated in lipid bilayers such as liposomes and inner mitochondrial membranes. The relative weight of this species in different media, as compared to porphyrin monomers and stacked aggregates, has been deduced by fluorescence decay studies. In contrast with what is observed for stacked aggregates, promotion of planar suprastructures can occur both in aqueous and lipid environments. The spectroscopic properties are very similar to those of the corresponding monomers, in particular as regards the shape of the absorption and emission spectra. The fluorescence decay times are generally higher than those of the monomers, and depend on the medium in which the planar aggregates are formed. The photooxidation properties of porphyrin planar aggregates, as revealed by oxygen consumption and histidine photodegradation upon irradiation at 365 nm, were compared to those of the monomers. The extent of the photooxidation process is nearly 20-30% higher in planar aggregates than in the monomers. In contrast, it is well known that cofacial aggregates are photochemically inert and only monomeric species of porphyrin are efficient photosensitizers. The biological relevance of these findings is discussed.
本文描述了对血卟啉和原卟啉非共价平面聚集体一些光物理性质的研究。这种卟啉物种最近被发现，并且可以在脂质双层如脂质体和线粒体内膜中产生。通过荧光衰减研究推断出该物种在不同介质中相对于卟啉单体和堆叠聚集体的相对重量。与堆叠聚集体的情况相反，平面超结构的形成在水性和脂质环境中均会发生。光谱性质与相应单体的光谱性质非常相似，特别是在吸收光谱和发射光谱的形状方面。荧光衰减时间通常高于单体的衰减时间，并且取决于形成平面聚集体的介质。通过在365nm照射时的耗氧量和组氨酸光降解揭示的卟啉平面聚集体的光氧化性质与单体的光氧化性质进行了比较。平面聚集体中的光氧化过程程度比单体中的高近20 - 30％。相比之下，众所周知，共面聚集体是光化学惰性的，只有卟啉的单体物种是有效的光敏剂。讨论了这些发现的生物学相关性。
