title: Determination of Singlet Oxygen and Electron Transfer Mediated  Mechanisms of Photosensitized Protein Damage by  Phosphorus(V)porphyrins.
abstract: The mechanism of photosensitized protein damage byphosphorus(V) tetraphenylporphyrin derivatives (P(V)TPPs) wasquantitatively clarified. P(V)TPPs bound to human serum albumin(HSA), a water-soluble protein, and damaged its tryptophan residueduring photoirradiation. P(V)TPPs photosensitized singlet oxygen ((1)O(2))generation, and the contribution of (1)O(2) to HSA damage was confirmedby the inhibitory effect of sodium azide, a (1)O(2) quencher. However,sodium azide could not completely inhibit HSA damage, suggesting thecontribution of an electron transfer mechanism to HSA damage. Thedecrement in the fluorescence lifetime of P(V)TPPs by HSA supportedthe electron transfer mechanism. The contribution of these processes could be determined by the kinetic analysis of the effect ofsodium azide on the photosensitized protein damage by P(V)TPPs.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Hironobu
authors.initials: H
authors.lastname: Umemoto
authors.forename: Ryo
authors.initials: R
authors.lastname: Kikuchi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Arai
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Okazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Segawa
mesh_terms: D004579:Electron Transport; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D010758:Phosphorus / Q000737:chemistry*; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry* / Q000528:radiation effects*; D026082:Singlet Oxygen / Q000032:analysis* / Q000378:metabolism; D019810:Sodium Azide / Q000494:pharmacology
chemical_list: D011166:Porphyrins; D012709:Serum Albumin; D026082:Singlet Oxygen; D010758:Phosphorus; D019810:Sodium Azide