
TY  - JOUR
A1  - Klimov, Vyacheslav V. 
A1  - Allakhverdiev, Suleyman I. 
A1  - Nishiyama, Yoshitaka 
A1  - Khorobrykh, Andrei A.  
A1  - Murata, Norio 
T1  - Stabilization of the oxygen-evolving complex of photosystem II by bicarbonate and glycinebetaine in thylakoid and subthylakoid preparations
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2003
VL  - 30
IS  - 7
SP  - 797
EP  - 803
KW  - bicarbonate, glycinebetaine, photosystem II, thermostability, water-oxidizing complex.
UR  - https://doi.org/10.1071/FP03068 
N2  - The protective effect of 1 M glycinebetaine on thermal inactivation of photosynthetic oxygen evolution in isolated photosystem II membrane fragments from spinach is observed in CO2-free medium in both the presence and absence of added 2 mM bicarbonate. Conversely, the protective effect of 2 mM bicarbonate against thermoinactivation is seen in the absence as well as in the presence of 1 M glycinebetaine. The stabilizing effect of bicarbonate is also observed in thylakoid membranes from Synechococcus sp. PCC 7002 treated with 0.1% Triton X-100, and in unbroken spinach thylakoids. It is shown for the first time that bicarbonate protects the water-oxidizing complex against inactivation induced by pre-incubation of photosystem II membrane fragments (25&#176;C) and thylakoids (40&#176;C) at low pH (5.0&#8211;5.5) in non-bicarbonate-depleted medium. We conclude that the protective effects of glycinebetaine and bicarbonate are of a different nature; glycinebetaine acts as a non-specific, compatible, zwitterionic osmolyte while bicarbonate is considered an essential constituent of the water-oxidizing complex of photosystem II, important for its functioning and stabilization. 
ER  -

