Anno2008
AutoriYoussef T. (1), Brazard J. (2), Ley C. (2), Lacombat F. (2), Plaza P.(2), M. Martin M. (2), Sgarbossa A. (3), Checcucci G. (3) and Lenci F. (3)
AbstractThe interaction of blepharismin (BP) and oxyblepharismin (OxyBP) with bovine alpha-crystallin (BAC) has been studied both by steady-state and femtosecond spectroscopy, with the aim of assessing the possible phototoxicity of these compounds toward the eye tissues. We showed that these pigments form with BAC potentially harmful ground-state complexes, the dissociation constants of which have been estimated to be 6 +/- 2 mumol L(-1) for OxyBP and 9 +/- 4 mumol L(-1) for BP. Irradiation with steady-state visible light of solutions of blepharismins in the presence of BAC proved to induce a quenching of both the pigment and the intrinsic protein fluorescences. These effects were tentatively rationalized in terms of structural changes of alpha-crystallin. On the other hand, femtosecond transient absorption spectroscopy was used to check the occurrence of any type I photoactivity of oxyblepharismin bound to alpha-crystallin. The existence of a particular type of fast photoinduced reaction, not observed in former studies with human serum albumin but present in the natural oxyblepharismin-binding protein, could here be evidenced but no specific reaction was observed during the first few nanoseconds after excitation. Partial denaturation of alpha-crystallin was however found to alter the excited-state behaviour of its complex with oxyblepharismin, making it partly resemble that of free oxyblepharismin in solution.
RivistaPhotochemical & Photobiological Sciences (print)
ISSN1474-905X
Impact factor
Volume7
Pagina inizio844
Pagina fine853
Autori IBFFrancesco LENCI, Giovanni CHECCUCCI, Antonella SGARBOSSA
Linee di Ricerca IBFMD.P01.003.001