Role of arginine 52 on the primary photoinduced events in the PYP photocycle

Pascale Changenet-Barret (1) , Pascal Plaza (1) , Monique M. Martin (1) , Haik Chosrowjan (2) , Seiji Taniguchi (2) , Noboru Mataga (2) , Yasushi Imamoto (3) , Mikio Kataoka (3)

1 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)
2 ILT - Institute for Laser Technology
3 Graduate School of Materials Science

We investigated the earliest steps of the photocycle of photoactive yellow protein (PYP) and its R52Q mutant in aqueous solution, by subpicosecond transient absorption spectroscopy. Our aim was to address the role of the positively charged Arg52 residue. We found that the relaxation mechanism of R52Q is similar to that of wt-PYP and discarded that Arg52 plays a key role in the chromophore photoreactivity. The excited-state decay of R52Q is however slower, confirming previous fluorescence up-conversion data. The experiments also reveal a slower stabilization of the cis isomer product. The loosening of the protein pocket and structural heterogeneities are discussed.

Domaines: Chimie théorique et/ou physique

Pascale Changenet-Barret, Pascal Plaza, Monique M. Martin, Haik Chosrowjan, Seiji Taniguchi, et al.. Role of arginine 52 on the primary photoinduced events in the PYP photocycle. Chemical Physics Letters, 2007, 434, pp.320. ⟨10.1016/j.cplett.2006.12.027⟩. ⟨hal-00126210⟩