Formation of Carotenoid Neutral Radicals in Photosystem II

Yunlong Gao, Katherine E. Shinopoulos, Cara A. Tracewell, A. Ligia Focsan, Gary W Brudvig, Lowell D. Kispert

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

β-Carotene radicals produced in the hexagonal pores of the molecular sieve Cu(II)-MCM-41 were studied by ENDOR and visible/near-IR spectroscopies. ENDOR studies showed that neutral radicals of β-carotene were produced in humid air under ambient fluorescent light. The maximum absorption wavelengths of the neutral radicals were measured and were additionally predicted by using time-dependent density functional theory (TD-DFT) calculations. An absorption peak at 750 nm, assigned to the neutral radical with a proton loss from the 4(4′) position of the β-carotene radical cation in Cu(II)-MCM-41, was also observed in photosystem II (PS II) samples using near-IR spectroscopy after illumination at 20 K. This peak was previously unassigned in PS II samples. The intensity of the absorption peak at 750 nm relative to the absorption of chlorophyll radical cations and β-carotene radical cations increased with increasing pH of the PS II sample, providing further evidence that the absorption peak is due to the deprotonation of the β-carotene radical cation. Based on a consideration of possible proton acceptors that are adjacent to β-carotene molecules in photosystem II, as modeled in the X-ray crystal structure of Guskov et al. Nat. Struct. Mol. Biol. 2009, 16, 334-342, an electron-transfer pathway from a β-carotene molecule with an adjacent proton acceptor to P680•+ is proposed.

Original languageEnglish
Pages (from-to)9901-9908
Number of pages8
JournalJournal of Physical Chemistry B
Volume113
Issue number29
DOIs
Publication statusPublished - Jul 23 2009

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carotenoids
Photosystem II Protein Complex
carotene
Carotenoids
Cations
Positive ions
Protons
cations
Multicarrier modulation
Infrared spectroscopy
protons
Deprotonation
Molecules
Molecular sieves
Chlorophyll
chlorophylls
absorbents
Density functional theory
spectroscopy
Lighting

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

Gao, Y., Shinopoulos, K. E., Tracewell, C. A., Focsan, A. L., Brudvig, G. W., & Kispert, L. D. (2009). Formation of Carotenoid Neutral Radicals in Photosystem II. Journal of Physical Chemistry B, 113(29), 9901-9908. https://doi.org/10.1021/jp8075832

Formation of Carotenoid Neutral Radicals in Photosystem II. / Gao, Yunlong; Shinopoulos, Katherine E.; Tracewell, Cara A.; Focsan, A. Ligia; Brudvig, Gary W; Kispert, Lowell D.

In: Journal of Physical Chemistry B, Vol. 113, No. 29, 23.07.2009, p. 9901-9908.

Research output: Contribution to journalArticle

Gao, Y, Shinopoulos, KE, Tracewell, CA, Focsan, AL, Brudvig, GW & Kispert, LD 2009, 'Formation of Carotenoid Neutral Radicals in Photosystem II', Journal of Physical Chemistry B, vol. 113, no. 29, pp. 9901-9908. https://doi.org/10.1021/jp8075832
Gao Y, Shinopoulos KE, Tracewell CA, Focsan AL, Brudvig GW, Kispert LD. Formation of Carotenoid Neutral Radicals in Photosystem II. Journal of Physical Chemistry B. 2009 Jul 23;113(29):9901-9908. https://doi.org/10.1021/jp8075832
Gao, Yunlong ; Shinopoulos, Katherine E. ; Tracewell, Cara A. ; Focsan, A. Ligia ; Brudvig, Gary W ; Kispert, Lowell D. / Formation of Carotenoid Neutral Radicals in Photosystem II. In: Journal of Physical Chemistry B. 2009 ; Vol. 113, No. 29. pp. 9901-9908.
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