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Proton Pathways in Green Fluorescence Protein Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
 

Summary: Proton Pathways in Green Fluorescence Protein
Noam Agmon
Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
ABSTRACT Proton pathways in green fluorescent protein (GFP) are more extended than previously reported. In the x-ray
data of wild-type GFP, a two-step exit pathway exists from the active site to the protein surface, controlled by a threonine switch.
A proton entry pathway begins at a glutamate-lysine cluster around Glu-5, and extends all the way to the buried Glu-222 near
the active site. This structural evidence suggests that GFP may function as a portable light-driven proton-pump, with proton
emitted in the excited state through the switchable exit pathway, and replenished from Glu-222 and the Glu-5 entry pathway in
the ground state.
INTRODUCTION
Proton pumps are a family of membrane proteins that play
a pivotal role in the bioenergetics of the cell (Wikstro¨m, 1998;
Decoursey, 2003; A¨ delroth and Brzezinski, 2004). Well-
known examples are bacteriorhodopsin (bR) and cytochrome
c oxidase (CcO), which convert light or chemical (2H21
O2/2H2O) energy, respectively, into a transmembranal
proton gradient, which subsequently drives ATP synthesis
(Wikstro¨m, 1998). The sequence of proton transfer (PT)
events, after photoexcitation of the bR chromophore (Cro),
involves conformational change in the Cro and its vicinity,

  

Source: Agmon, Noam - Institute of Chemistry, Hebrew University of Jerusalem

 

Collections: Chemistry