Calcium EXAFS establishes the Mn-Ca cluster in the oxygen-evolving complex of Photosystem II

Journal Article · Fri Aug 02 04:00:00 EDT 2002 · Biochemistry

DOI:https://doi.org/10.1021/bi026569p· OSTI ID:805137

Cinco, Roehl M ^[1]; McFarlane Holman, Karen L; Robblee, John H; Yano, Junko; Pizarro, Shelly A; Bellacchio, Emanuele; Sauer, Kenneth; Yachandra, Vittal K

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1. LBNL Library

The proximity of Ca to the Mn cluster of the photosynthetic water-oxidation complex is demonstrated by X-ray absorption spectroscopy. We have collected EXAFS data at the Ca K-edge using active PS II membrane samples that contain approximately 2 Ca per 4 Mn. These samples are much less perturbed than previously investigated Sr-substituted samples, which were prepared subsequent to Ca depletion. The new Ca EXAFS clearly shows backscattering from Mn at 3.4 angstroms, a distance that agrees with that surmised from previously recorded Mn EXAFS. This result is also consistent with earlier related experiments at the Sr K-edge, using samples that contained functional Sr, that show Mn is {approx}; 3.5 angstroms distant from Sr. The totality of the evidence clearly advances the notion that the catalytic center of oxygen evolution is a Mn-Ca heteronuclear cluster.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director, Office of Science. Office of Basic Energy Studies. Chemical Sciences, Geosciences, and Biosciences Division; National Institutes of Health (US)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 805137
• Report Number(s): LBNL--51252; B& R 400412000
• Journal Information: Biochemistry, Journal Name: Biochemistry Journal Issue: 43 Vol. 41
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ABSORPTION SPECTROSCOPY
BACKSCATTERING
CALCIUM
COMPLEX
EDGE
ELECTRON
EPR
EVOLVING
EXAFS
EXTENDED
FINE
FOURIER
FT
FUNCTIONALS
II
LHC
LIGHT-HARVESTING
MEMBRANES
MLS
MULTILINE
NEAR
OEC
OXYGEN
PARAMAGNETIC
PHOTOSYSTEM
PS
RESONANCE
SIGNAL
SPECTROSCOPY
STRUCTURE
TRANSFORM
X-RAY
XANES
XAS