光合作用I概要.ppt

The generation of ATP - ATP Synthase A multi-subunit protein complex CFO and CF1 Molecular motor 高等植物PSII的集光叶绿素蛋白复合体(LHCII) LHCII是PSII的天线色素-蛋白复合体，高等植物中LHCII的天然生理状态主要是以三聚体的形式存在。每个LHCII单体多肽有3个跨膜的а螺旋部分，其中两个通过带电AA相互结合，同时也维持了chla和chlb间的紧密接触和取向，保证激发能的快速传递（见图）。 The generation of NADPH- Cyclic photophosphorylation The generation of NADPH- Cyclic photophosphorylation Non-cyclic photophosphorylation Ferredoxin (Fd) No production of NADPH Proton translocation 7. 假循环电子传递 当植物在高光强或低温引起碳同化降低，NADP+ 缺乏等环境下，水光解产生的电子由PSⅡ传到PSⅠ时，电子没有传递给NADP+ ，而是传递给分子氧，形成超氧自由基（O2-），在体内 O2-具有毒害作用，可通过超氧化物歧化酶（SOD）清除，同时产生H2O2， H2O2可通过抗坏血酸—过氧化酶系统被清除，形成H2O，似乎电子是从H2O → H2O循环，故也称为水→水循环（Mehler反应）。 （1）2H2O → 4e- + 4H+ + O2 [PSⅡ的水光氧化] （2）2O2 + 2e- → 2O2- [PSI的O2光还原] （3）2O2- + 2H+ → H2O2 + O2 [SOD催化的歧化作用] （4）H2O2 + 2ascorbate(Vc) → 2H2O + 2MDA(单脱水抗坏血酸,MDHA) [抗坏血酸过氧化物酶(APX)催化的H2O2被VC还原] （5）2MDA(or DHA) + 2e- + 2H+ → 2Vc ∑2H2O (PSⅡ) + O2* (PS?)→ O2 + 2H2O* (PSI) The generation of ATP - The Jagendorf experiment The generation of ATP - The Jagendorf experiment Stroma pH=8 Lumen pH=4 The difference of pH is sufficient to drive ATP synthesis. The generation of ATP– The generation of proton gradient Stroma side: lower [H+], Higher pH Lumen side: higher [H+], lower pH Two sites for H+ generation: Oxygen Evolving Complex Cytochrome b6f Complex The generation of ATP– Proton motive force (pmf) ?p = ?E + ?pH ?p: pmf ?E: electric potential ?pH: pH difference Lumen Stroma 光和光谱 （Light and Light Spectrum） Light - Electromagnetic Spectrum The higher the frequency, the higher the energy. The longer the wavelength, the lower the energy. E = h? E = Energy h = Planck’s constant ? = Frequency ? = ?-1 Photosynthetic Pigments - Absorption spectrum You can measure how much light is absorbed (A) Or how much light is transmitted (T) A spectrophotometer A NanoDrop Phot