Ultrafast carbonyl motion of the Photoactive Yellow Protein chromophore probed by femtosecond circular dichroism
Résumé
Motions of the trans-p-coumaric acid carbonyl group following the photoexcitation of the R52Q mutant of Photoactive Yellow Protein (PYP) are investigated, for the first time, by ultrafast time-resolved circular dichroism (TRCD) spectroscopy. TRCD is monitored in the near ultraviolet, over a timescale of 10 ps. Immediately after excitation, TRCD is found to exhibit a large negative peak, which decays within a few picoseconds. A quantitative analysis of the signals shows that, upon excitation, the carbonyl group undergoes a fast (<