An ESEEM study of the oxidized electron donor of plant photosystem II: Evidence that D is a neutral tyrosine radical

1989 ◽  
Vol 161 (6) ◽  
pp. 479-484 ◽  
Author(s):  
R.G. Evelo ◽  
A.J. Hoff ◽  
S.A. Dikanov ◽  
A.M. Tyryshkin
Keyword(s):  
Photosystem Ii ◽  
Electron Donor ◽  
Tyrosine Radical

Effect of Magnesium and Calcium Ions on the Photoelectron Transport Activity of Low-Salt Suspended Hydrilla verticillata Thylakoids: Possible Sites of Cation Interaction

1998 ◽  
Vol 53 (9-10) ◽  
pp. 849-856
Author(s):  
Sujata R. Mishra ◽  
Surendra Chandra Sabat
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Donor ◽  
Water Oxidation ◽  
Electron Flow ◽  
Hydrilla Verticillata ◽  
Transport Activity ◽  
Low Salt ◽  
Electron Transport Activity ◽  
Stimulation Of

Stimulatory effect of divalent cations like calcium (Ca2+) and magnesium (Mg2+) was investigated on electron transport activity of divalent cation deficient low-salt suspended (LS) thylakoid preparation from a submerged aquatic angiosperm, Hydrilla verticillata. Both the cations stimulated electron transport activity of LS-suspended thylakoids having an intact water oxidation complex. But in hydroxylamine (NH2OH) - or alkaline Tris - washed thylakoid preparations (with the water oxidation enzyme impaired), only Ca2+ dependent stimulation of electron transport activity was found. The apparent Km of Ca2+ dependent stimulation of electron flow from H2O (endogenous) or from artificial electron donor (exogenous) to dichlorophenol indophenol (acceptor) was found to be identical. Calcium supported stimulation of electron transport activity in NH2OH - or Tris - washed thylakoids was electron donor selective, i.e., Ca2+ ion was only effective in electron flow with diphenylcarbazide but not with NH2OH as electron donor to photosystem II. A magnesium effect was observed in thylakoids having an intact water oxidation complex and the ion became unacceptable in NH2OH - or Tris - washed thylakoids. Indirect experimental evidences have been presented to suggest that Mg2+ interacts with the water oxidation complex, while the Ca2+ interaction is localized betw een Yz and reaction center of photosystem II.

scholarly journals Photosystem II single crystals studied by EPR spectroscopy at 94 GHz: The tyrosine radical YFormula

2001 ◽  
Vol 98 (12) ◽  
pp. 6623-6628 ◽  
Author(s):  
W. Hofbauer ◽  
A. Zouni ◽  
R. Bittl ◽  
J. Kern ◽  
P. Orth ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Single Crystals ◽  
Epr Spectroscopy ◽  
Tyrosine Radical

The τ-Nitrogen of D2 Histidine 189 is the Hydrogen Bond Donor to the Tyrosine Radical YD•of Photosystem II

1997 ◽  
Vol 119 (20) ◽  
pp. 4787-4788 ◽  
Author(s):  
Kristy A. Campbell ◽  
Jeffrey M. Peloquin ◽  
Bruce A. Diner ◽  
Xiao-Song Tang ◽  
Dexter A. Chisholm ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Photosystem Ii ◽  
Hydrogen Bond Donor ◽  
Tyrosine Radical
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