2pyr: Difference between revisions

Photoactive yellow protein (PYP) is a member of the xanthopsin family of, eubacterial blue-light photoreceptors. On absorption of light, PYP enters, a photocycle that ultimately transduces the energy contained in a light, signal into an altered biological response. Nanosecond time-resolved x-ray, crystallography was used to determine the structure of the short-lived, red-shifted, intermediate state denoted [pR], which develops within 1, nanosecond after photoelectronic excitation of the chromophore of PYP by, absorption of light. The resulting structural model demonstrates that the, [pR] state possesses the cis conformation of the 4-hydroxyl cinnamic, thioester chromophore, and that the process of trans to cis isomerization, is accompanied by the specific formation of new hydrogen bonds that, replace those broken upon excitation of the chromophore. Regions of, flexibility that compose the chromophore-binding pocket serve to lower the, activation energy barrier between the dark state, denoted pG, and [pR], and help initiate entrance into the photocycle. Direct structural evidence, is provided for the initial processes of transduction of light energy, which ultimately translate into a physiological signal.

2PYR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halorhodospira_halophila Halorhodospira halophila] with HC4 as [http://en.wikipedia.org/wiki/ligand ligand]. Structure known Active Site: CRE. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2PYR OCA].  

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