First-principles characterization of the energy landscape and optical spectra of green fluorescent protein along the AâIâB proton transfer route.
J Am Chem Soc
; 135(31): 11541-9, 2013 Aug 07.
Article
em En
| MEDLINE
| ID: mdl-23837665
ABSTRACT
Structures and optical spectra of the green fluorescent protein (GFP) forms along the proton transfer route AâIâB are characterized by first-principles calculations. We show that in the ground electronic state the structure representing the wild-type (wt) GFP with the neutral chromophore (A-form) is lowest in energy, whereas the systems with the anionic chromophore (B- and I-forms) are about 1 kcal/mol higher. In the S65T mutant, the structures with the anionic chromophore are significantly lower in energy than the systems with the neutral chromophore. The role of the nearby amino acid residues in the chromophore-containing pocket is re-examined. Calculations reveal that the structural differences between the I- and B-forms (the former has a slightly red-shifted absorption relative to the latter) are based not on the Thr203 orientation, but on the Glu222 position. In the case of wt-GFP, the hydrogen bond between the chromophore and the His148 residue stabilizes the structures with the deprotonated phenolic ring in the I- and B-forms. In the S65T mutant, concerted contributions from the His148 and Thr203 residues are responsible for a considerable energy gap between the lowest energy structure of the B type with the anionic chromophore from other structures.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hidrozoários
/
Proteínas de Fluorescência Verde
/
Corantes Fluorescentes
Limite:
Animals
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2013
Tipo de documento:
Article