CIOP   05384
CENTRO DE INVESTIGACIONES OPTICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Time resolved photoacoustics applied to the study of photoinduced electron transfer processes in cytochrome c - CuA subunit of cytocrome oxidase system
Autor/es:
SERRANO, EMILIA; DAVID GARA, PEDRO M.; BILMES, GABRIEL; BRASLAVSKY, SILVIA
Lugar:
Pucon
Reunión:
Congreso; IX Iberoamerican Meeting on Optics and XII Iberoamerican Meeting on Optics, Lasers and Applications; 2016
Resumen:
The long-range (10 to 25 Å) charge transfer in protein complexes is a very important process in respiratory and photosynthetic machinery. Little is known about the effects and contributions of the environment in these long-range interactions, as well as the influence of the separation between the donor (D) and acceptor (A) partners. As a part of an ongoing project, the mechanisms of energy conversion and structural movements in modified proteins due to charge transfer are studied by laser-induced optoacoustic spectroscopy (LIOAS). Photoacoustic measurements as a function of the temperature are performed by using nanosecond low energy laser pulses and piezoelectric detection. Deconvolution methods for signal analysis, in combination with an appropriate model, allows the determination of structural volume changes during the transfer of electrons between the donor and acceptor. We show preliminary results obtained with the CuA center of cytochrome oxidase subunit II [1] and the cytochrome c. Three well-separated processes were identified: a fast one (prompt) with a decay time τ1 ≤ 10 ns; a slower process with a lifetime τ2 ca. 200-400 ns; and a longest-lived component with a lifetime longer than 1 µs. The pre-exponential factors φi of the three components at several temperatures were plotted as Eλ φi vs (cpρ/β). In all cases, good linear correlations were obtained. The slopes of the lines represent the structural volume change associated with each of the processes, in each case multiplied by the respective quantum yield of the process. Results are com-plemented with kinetic and thermodynamic studies in order to have a better understanding of the photophysical and photochemical behavior of these systems.