title: Photosensitization of liposomal membranes by hematoporphyrin derivative.
abstract: The putative tumor-localizing and -photosensitizing fraction of hematoporphyrin derivative, the fastest migrating fraction of hematoporphyrin derivative separated by polyacrylamide gel filtration (HPD-A), photosensitized lipid peroxidation and membrane lysis in egg phosphatidylcholine liposomes. The rate of membrane damage was approximately 4-fold faster in oxygen compared to anoxia, with evidence for the involvement of singlet oxygen. The diffusion of HPD-A into small liposomes led to a shift of the Soret band from 363 nm in buffer to 398 nm accompanied by 4-fold enhancement of the fluorescence. The presence of human serum albumin retarded the diffusion of HPD-A into small liposomes, which is attributed to partial complexing of the HPD-A. A different effect of serum albumin was the protection of large liposomes from photosensitized lysis by incorporated HPD-A. This protection is attributed to scavenging of singlet oxygen, as evidenced by oxidation of tryptophan in the protein.
mesh_terms: D000818:Animals; D004530:Egg Yolk; D005260:Female; D017324:Hematoporphyrin Derivative; D006415:Hematoporphyrins; D007700:Kinetics; D008081:Liposomes / Q000528:radiation effects; D010713:Phosphatidylcholines; D010782:Photolysis; D011838:Radiation-Sensitizing Agents
chemical_list: D006415:Hematoporphyrins; D008081:Liposomes; D010713:Phosphatidylcholines; D011838:Radiation-Sensitizing Agents; D017324:Hematoporphyrin Derivative