Fluorescence Spectroscopy, Exciton Dynamics and Photochemistry of Single Allophycocyanin Trimers

Journal Article · Thu Jan 01 00:00:00 EST 1998 · Journal of Physical Chemistry B

DOI:https://doi.org/10.1021/jp983227d· OSTI ID:15001947

Ying, Liming ^[1]; Xie, Xiaoliang ^[2]

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1. ASSOC WESTERN UNIVERSITY
2. HARVARD UNIVERSITY

We report a study of the spectroscopy and exciton dynamics of the allophycocyanin trimer (APC), a light harvesting protein complex from cyanobacteria, by room-temperature single-molecule measurements of fluorescence spectra, lifetimes, intensity trajectories and polarization modulation. Emission spectra of individual APC trimers are found to be homogeneous on the time scale of seconds. In contrast, their emission lifetimes are found to be widely distributed, because of generation of exciton traps during the course of measurements. The intensity trajectories and polarization modulation experiments indicate reversible ixciton trap formation within the three quasi-independent pairs of strong interacting a84 and B84 chromophores in APC, as well a photobleaching of individual chromophores. Comparison experiments under continuous wave and pulsed excitation reveal a two-photon mechanism for generating exciton traps and/or photobleaching, which involves exciton-exciton annihilation. These single-molecule experiments provide new insights into exciton dynamics and photochemistry of light-harvesting complexes.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15001947
• Report Number(s): PNNL-SA-30274; KC0301020; TRN: US0400537
• Journal Information: Journal of Physical Chemistry B, Vol. 102, Issue 50; Other Information: PBD: 1 Jan 1998
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANNIHILATION
CYANOBACTERIA
EMISSION SPECTRA
EXCITATION
EXCITONS
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
HARVESTING
MODULATION
PHOTOCHEMISTRY
POLARIZATION
PROTEINS
SPECTRA
SPECTROSCOPY
TRAJECTORIES