PSⅡ中蛋白二级结构中β聚合效应的红外光谱研究

利用Fourier变换红外光谱（FTIR）方法研究了光系统Ⅱ（PSⅡ）膜颗粒中蛋白二级结构在高温条件下的β聚合效应。具有生物活性和高温蛋白的β聚合样品的红外光谱测量温度均是室温，它们的酰胺Ⅰ吸收带被用来对两种样品的特性进行定量的分析。光谱的分析方法采用了直接Lorentz线型拟合，光谱结果表明光系统Ⅱ二级结构在400℃下发生热变性后，其红外光谱将发生很强的不可逆的变化。但其红外光谱与活性PSⅡ蛋白一样仍可用3个Lorentz线型拟合，显示了FTIR红外光谱方法在研究蛋白热变性方面的优越性。     

RELATIONSHIP BETWEEN THE CHANGES OF THE FAST PHASE OF MILLISECOND DELAYED LIGHT EMISSION AND THE PROTON RELEASED BY THE OXIDATION OF WATER

The phosphorylation uncouplers suppressing the proton gradient across the thylakoidmembrane can also affect the fast phase of millisecond delayed light emission (ms-DLE) atflash light intensity strong enough to saturate the Hill reaction. At the concentration ofsame uncoupling degree, nigericin decreases the fast phase DLE much more than NH_4Cl.Omitting the terminal acceptor in the reaction mixture or adding DBMIB to inhibit PQ oxi-dation diminishes the slow phase DLE and affects the fast phase slightly, while DCMU orHOQNO which inhibits electron transport between PSII and PQ, diminishes both phases ofms-DLE. These results indicate that the proton gradient responsible for the enhancement ofthe fast phase DLE is more intimately linked to the thylakoid membrane, and is mainlyrelated to the proton release from water oxidation and not to the turnover of plastoquinone.     

叶绿体毫秒级延迟发光的快相变化与水氧化时质子释放的关系的研究

本文证明在希尔反应速度饱和的强闪光下,消除膜两侧质子浓度差的解联剂也影响毫秒级延迟发光的快相。在对磷酸化解联程度相仿时,尼日利亚菌素对快相的消除作用大于氯化铵。光系统Ⅱ至质醌间的电子传递抑制剂同时降低快相及慢相延迟发光,抑制还原的质醌氧化的二溴百里香醌或不加电子受体使光合电子传递末端受阻则只降低慢相,而对快相影响很少。这表明影响快相的质子浓度差与膜联系紧密,且主要与光系统Ⅱ水氧化时的质子释放有关。