Effect of the 17- and 23-kilodalton polypeptides, calcium, and chloride on electron transfer in photosystem II

Journal Article · Tue Oct 21 04:00:00 EDT 1986 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00369a022· OSTI ID:6525111

de Paula, J C; Li, P M; Miller, A F; Wu, B W; Brudvig, G W

Electron paramagnetic resonance (EPR) measurements were performed on photosystem II (PSII) membranes that were treated with 2 M NaCl to release the 17- and 23-kilodalton (kDa) polypeptides. By using 75 ..mu..M 3-(3,4-dichlorophenyl)-1,1-dimethylurea to limit the photosystem II samples to one stable charge separation in the temperature range of 77-273 K, the authors have quantitated the EPR signals of the several electron donors and acceptors of photosystem II. It was found that removal of the 17- and 23-kDa polypeptides caused low potential cytochrome b/sub 559/ to become fully oxidized during the course of dark adaptation. Following illumination at 77-130 K, one chlorophyll molecule per reaction center was oxidized. Between 130 and 200 K, both a chlorophyll molecule and the S/sub 1/ state were photooxidized and, together, accounted for one oxidation per reaction center. Above 200 K, the chlorophyll radical was unstable. Oxidation of the S/sub 1/ state gave rise to the S/sub 2/-state multiline EPR signal, which arises from the Mn site of the O/sub 2/-evolving center. The yield of the S/sub 2/-state multiline EPR signal in NaCl-washed PSII membranes was as high as 93% of the control, untreated PSII membranes, provided that both Ca/sup 2 +/ and Cl/sup -/ were bound. Furthermore, the /sup 55/ Mn nuclear hyperfine structure of the S/sub 2/-state multiline EPR signal was unaltered upon depletion of the 17- and 23-kDa polypeptides. In NaCl-washed PSII samples where Ca/sup 2 +/ and/or Cl/sup -/ were removed, however, the intensity of the S/sub 2/-state multiline EPR signal decreased in parallel with the fraction of PSII lacking bound Ca/sup 2 +/ and Cl/sup -/. They conclude that Ca/sup 2 +/ and Cl/sup -/, and not the 17- and 23-kDa polypeptides, are the main factors governing the ability to observed the S/sub 2/-state multiline EPR signal.

• Research Organization: Yale Univ., New Haven, CT
• OSTI ID: 6525111
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 25:21; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BIOCHEMISTRY
CALCIUM COMPOUNDS
CARBOXYLIC ACIDS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CHLOROPHYLL
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
ELEMENTS
FOOD
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYPERFINE STRUCTURE
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAGNETIC RESONANCE
MANGANESE 55
MANGANESE ISOTOPES
MEMBRANES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN
PEPTIDES
PHOTOSYNTHETIC MEMBRANES
PHOTOSYNTHETIC REACTION CENTERS
PHYTOCHROMES
PIGMENTS
PLANTS
POLYPEPTIDES
PORPHYRINS
PROTEINS
RESONANCE
SODIUM CHLORIDES
SODIUM COMPOUNDS
SPINACH
STABLE ISOTOPES
TRACER TECHNIQUES
VALENCE
VEGETABLES