Issue 47, 2017

Electronic structure and dynamics of torsion-locked photoactive yellow protein chromophores

Abstract

The photocycle of photoactive yellow protein (PYP) begins with small-scale torsional motions of the chromophore leading to large-scale movements of the protein scaffold triggering a biological response. The role of single-bond torsional molecular motions of the chromophore in the initial steps of the PYP photocycle are not fully understood. Here, we employ anion photoelectron spectroscopy measurements and quantum chemistry calculations to investigate the electronic relaxation dynamics following photoexcitation of four model chromophores, para-coumaric acid, its methyl ester, and two analogues with aliphatic bridges hindering torsional motions around the single bonds adjacent to the alkene group. Following direct photoexcitation of S1 at 400 nm, we find that both single bond rotations play a role in steering the PYP chromophore through the S1/S0 conical intersection but that rotation around the single bond between the alkene moiety and the phenoxide group is particularly important. Following photoexcitation of higher lying electronic states in the range 346–310 nm, we find that rotation around the single bond between the alkene and phenoxide groups also plays a key role in the electronic relaxation from higher lying states to the S1 state. These results have potential applications in tuning the photoresponse of photoactive proteins and materials with chromophores based on PYP.

Graphical abstract: Electronic structure and dynamics of torsion-locked photoactive yellow protein chromophores

Supplementary files

Article information

Article type
Paper
Submitted
11 okt 2017
Accepted
16 nov 2017
First published
16 nov 2017
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2017,19, 31572-31580

Electronic structure and dynamics of torsion-locked photoactive yellow protein chromophores

A. Henley, M. E. Diveky, A. M. Patel, M. A. Parkes, J. C. Anderson and H. H. Fielding, Phys. Chem. Chem. Phys., 2017, 19, 31572 DOI: 10.1039/C7CP06950B

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