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The differences between hydroxylamin and hydrazine in affecting oxygen evolution of photosynthetic water splitting system in tobacco

He Ping

Central-South Forestry University.Zhuzhou 412006,Hunan

Abstract

The effects of hydroxylamine and hydrazine on oxygen evolution by photosynthetic water splitting system in tobacco (Nicoltiana tobacum L.cv.JWB)were compared by means of a three-electrode system. The results showed that there were some differences in the way and the degree to which these two agents affected oxygen evolution.The reactivity of hydroxylamine to S-state system was stronger than that of hydrazine. Hydroxylamine caused two digit shift in the redox potential of S-state system,which reduced S_0 to S_2,and hydrazine only from S_0 to S_(-1).Hydrazine showed very strong inhibitive effect on photosynthetic water splitting.It means that the affinity of hydrazine for water splitting centre is strong and that the destroying effects of it on the centre is also strong. The inhibition of photosynthetic water splitting by hydroxylamine was so slight that even at a concentration of 1 000 #mu#mol/L there were still strong oxygen evolution signals.The effects of hydroxylamine in inducing oxygen uptake were also weak.DCMU inhibited S_0,S_1 and S_2,but not S_3 which shows that hydroxylamine and hydrazine are undergo the same photo-oxidising process as water does in PS Ⅱ.

Key words: Tobacco;Photosynthetic water splitting;Hydroxylamine;Hydrazine

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Citing This Article：

He Ping. The differences between hydroxylamin and hydrazine in affecting oxygen evolution of photosynthetic water splitting system in tobacco. Acta Physiol Sin 1996; 48 (2): (in Chinese with English abstract).