摘要
羟胺对Ｓ状态系统的还原作用比肼强，它可将水裂解的Ｓ状态系统从Ｓ０还原到Ｓ－２，肼只能将Ｓ０还原到Ｓ－１。肼对光合水裂解的抑制作用较羟胺强。在高浓度下（１０００μｍｏｌ／Ｌ）它可完全抑制光合水裂解，使烟草叶绿体产生强烈的氧吸收。羟胺可使暗适应叶绿体的Ｓ状态系统的Ｓｉ（ｉ＝１～４）分布趋向稳态。高浓度羟胺（１０００μｍｏｌ／Ｌ）仍不能完全抑制氧释放，并且对叶绿体氧吸收的诱导作用也很小。
The effects of hydroxylamine and hydrazine on oxygen evolution by photosynthetic water splitting system in tobacco (Nicotiana tabacum L. cv. JWB)were compared by means of a threeelectrode system. The results showedthat there were some differences in theway and the degree to which these twoagents affected oxygen evolution.:hereactivity of hydroxylamine to S-statesystem was stronger than that of hydrazine. Hydroxylamine caused twodigit shift in the redox potential of Sstate system, which reduced S0 to S2,and hydrazine only from So to S-1(Figs. 2, 4 ). Hydrazine showed verystrong inhibitive effect on photosynthetic water splitting. At a concentration of50 μmol/L, oxygen uptake signals oftobacco chloroplasts appeared under thefirst and second flashes which increasedwith an increase of concentration (Fig.2 ). When the concentration reached1 000 μmol/L, the water splitting reaction under flash light was inhibitedcompletely, only strong oxygen uptakesignals were observed (Fig. 3 ). It meansthat the affinity of hydrazine for watersplitting centre is strong and that the destroying effects of it on the centre is also strong. The inhibition of photosynthetic water splitting by hydroxylaminewas so slight that even at a concentration of 1 000 μmol/L there were stillstrong oxygen evolution signals (Fig.5 ). The effects of hydroxylamine ininducing oxygen uptake were alsoweak. Even at a concentration of 1 000μmol/L only weak oxygen uptake signalwas detected (Fig. 5 ). Hydroxylamineinduced dark stable S3. With increasingconcentration, the population of S3 increased, and the redox potential of Sstate system approached its steady state.At a concentration of 1 000 μmol/L,the oxygen evolution pattern reachedthe steady state, which implies that thepopulation of S, (i = 1 ￣ 4 ) reachedabout 25%, and the detected signal ofdark stable S3 was even stronger thanthose of the others. DCMU inhibitedS0, S1 and S2, but not S3 (Fig. 6 ),which shows that hydroxylamine andhydrazine are undergo the same photooxidising process as water does in PSⅡ.
基金
法国国际人类前沿科学计划组织资助
关键词
烟草
羟胺
肼
光合作用
光合放氧
tobacco, photosynthetic water splitting,hydroxylamine, hydrazine.
