Thumbnail
Access Restriction
Open

Author Niedzwiedzki, Dariusz M. ♦ Liu, Haijun ♦ Blankenship, Robert E.
Sponsorship USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher American Chemical Society
Language English
Subject Keyword SOLAR ENERGY
Abstract The orange carotenoid protein (OCP) is a 35 kDa water-soluble protein involved in a photoprotective mechanism of the photosynthetic apparatus of cyanobacteria. The OCP contains a single molecule of the carotenoid 3'-hydroxyechinenone (3'-hECN). We have performed transient absorption studies at 77 K in the visible and near-infrared spectral ranges on 3'-hECN in solvent glass and in both inactive (orange) and active (red) forms of OCP. In the OCP the cryogenic temperature prohibited the protein from spontaneous conversion between activity stages and allowed us to study well-defined spectral forms of the protein. The studies show that each form of the OCP consists of two protein subpopulations having different photophysical properties of the bound 3'-hECN. At 77 K the inactive OCP reveals two lifetimes of the first excited state of 3'-hECN of 5.2 and 11 ps while in the active form of OCP these are 3.2 and 7.1 ps. We have also determined the energy of the first excited singlet state of 3'-hECN in long-lived subpopulations of both OCP forms at 77 K. This is 13,750 cm<sup>–1</sup> in the inactive OCP and 12,300 cm<sup>-1</sup> in the active OCP. Shortening of the lifetime and decrease of the energy of the first excited singlet state of 3'-hECN confirm the lengthening of the effective conjugation of the carotenoid upon the inactive-to-active conversion of OCP.
ISSN 15206106
Educational Use Research
Learning Resource Type Article
Publisher Date 2014-06-12
Publisher Place United States
Journal Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Volume Number 118
Issue Number 23
Technical Publication No. DOE/SC0001035-111
Organization Blankenship/Washington Univ., St. Louis, MO (United States) ♦ Photosynthetic Antenna Research Center (PARC)


Open content in new tab

   Open content in new tab