Format

Send to

Choose Destination
Protein Sci. 2012 Feb;21(2):171-7. doi: 10.1002/pro.762. Epub 2011 Dec 21.

A conserved interaction with the chromophore of fluorescent proteins.

Author information

1
Graduate Program in Biophysics, University of Wisconsin-Madison, Madison, WI 53706, USA.

Abstract

The chromophore of fluorescent proteins, including the green fluorescent protein (GFP), contains a highly conjugated imidazolidinone ring. In many fluorescent proteins, the carbonyl group of the imidazolidinone ring engages in a hydrogen bond with the side chain of an arginine residue. Prior studies have indicated that such an electrophilic carbonyl group in a protein often accepts electron density from a main-chain oxygen. A survey of high-resolution structures of fluorescent proteins indicates that electron lone pairs of a main-chain oxygen-Thr62 in GFP-donate electron density into an antibonding orbital of the imidazolidinone carbonyl group. This n→π* electron delocalization prevents structural distortion during chromophore excitation that could otherwise lead to fluorescence quenching. In addition, this interaction is present in on-pathway intermediates leading to the chromophore, and thus could direct its biogenesis. Accordingly, this n→π* interaction merits inclusion in computational and photophysical analyses of the chromophore, and in speculations about the molecular evolution of fluorescent proteins.

PMID:
22057893
PMCID:
PMC3324761
DOI:
10.1002/pro.762
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center