Conformation of self-assembled porphyrin dimers in liposome vesicles by phase-modulation 2D fluorescence spectroscopy.
Proc Natl Acad Sci U S A
; 108(40): 16521-6, 2011 Oct 04.
Article
en En
| MEDLINE
| ID: mdl-21940499
ABSTRACT
By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a "T-shaped" geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation.
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1
Base de datos:
MEDLINE
Asunto principal:
Porfirinas
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Conformación Proteica
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Espectrometría de Fluorescencia
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Multimerización de Proteína
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Liposomas
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Modelos Biológicos
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2011
Tipo del documento:
Article