On the question of the chlorophyll a content of the photosystem II reaction center

Journal Article · Thu Aug 04 04:00:00 EDT 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100082a051· OSTI ID:6939278

Chang, H C; Jankowiak, R; Reddy, N R.S.; Small, G J ^[1]; Yocum, C F ^[2]; Picorel, R ^[3]; Seibert, M ^[4]

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1. Ames Lab.-USDOE, IA (United States) Iowa State Univ., Ames, IA (United States)
2. Univ. of Michigan, Ann Arbor, MI (United States)
3. CSIC, Zaragoza (Spain) National Renewable Energy Lab., Golden, CO (United States)
4. National Renewable Energy Lab., Golden, CO (United States)

Isolation procedures have led to chlorophyll a (Chl a) contents of the photosystem II reaction center (RC) that range between about 4 and 6. Since this content for the bacterial RC is 4 (with two of those being associated with the special pair), the nature of the [open quotes]extra[close quotes] Chl a in RC preparations of photosystem II containing more than 4 Chl a molecules is currently of much interest. So too are the dynamics of primary charge separation in the RC which are triggered by excitation of the primary electron donor state, P680* (where P680 indicates that the lowest energy ground-state absorption band of the primary donor lies at 680 nm; the asterisk indicates lowest lying [sup 1][pi][pi]* (Q[sub y]) state). We report absorption and triplet-state bottleneck hole spectra (4.2 K) for RC preparations of photosystem II containing 4, 5, and 6 Chl a molecules. The spectra reveal that the extra Chl a are due to 684-nm-absorbing Chl a, some contamination by the proximal antenna protein complex CP47, and, probably, also nonnative (disrupted) Chl a absorbing near 670 nm. The 684-nm Chl a were found to be easily disrupted by the ionic detergent Triton X-100 (much more so than P680). The results are inconsistent with the model that has the 684-nm band being the dimer (special pair) partner of P680. 73 refs., 10 figs.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6939278
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:31; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

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ABSORPTION SPECTRA
ADDITIVES
BACTERIA
CARBOXYLIC ACIDS
CHLOROPHYLL
COMPLEXES
COUPLING
DETERGENTS
ELECTRON-PHONON COUPLING
EMULSIFIERS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LIFETIME
MICROORGANISMS
MULTIPLETS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC REACTION CENTERS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
SPECTRA
SURFACTANTS
TRIPLETS
WETTING AGENTS