Lecture Series 4 on the Basics of Photosynports: Electron Transfer and Photophate Phosphate

primary reaction separates the charge at the reaction center of the optical system, and the high-energy electrons produced push the electrons on the photohealth membrane. The result of electron transmission, on the one hand, causes the cracking of water to free oxygen and the reduction of NADP plus, on the other hand, the proton dynamic potential of trans-membrane is established, and the photohealth
phosphatization
is initiated to form ATP. This converts electrical energy
into
active chemical energy.
First, electron and proton transfer
(i) photosynthetic chain
the so-called photosynthetic chain refers to the total trajectory of electron transmission, consisting of multiple electron transfer bodies, located on the photosynthesis membrane. Now more recognized by Hill (1960) and others proposed and revised and supplemented by the "Z" scheme ("Z" scheme), that is, the electronic transmission is done in series with two optical systems, the electronic transfer body according to the redox may be arranged, so that the electronic transmission chain is written on the side of the "Z" shape.
transmission mode in the emerald can be seen: (1) the electron transfer chain is mainly composed of PSII., Cyt b6/f, PSI. three complexes on the photoclithing membrane in series. (2) There are two areas of electron transmission is the reverse potential gradient, that is, P680 to P680, P700 to P700, the "uphill" electron transmission of this reverse potential gradient is driven by the fusion pigment complex after absorbing light energy, while the rest of the electron transmission is carried out by the home potential gradient. (3) The oxidation of water is related to PSII.electronic transmission, and the reduction of NADP-plus is related to PSI.electronic transmission. When the final supply of electrons is water, when water is oxidized, 4 electrons are transmitted to PSII. The final subject of the electron is NADP plus. (4) PQ is a dual-electron dual-H-plus transfer body, which is accompanied by electron transmission, which takes H-plus from the cystic membrane to the membrane, together with the H-plus produced by water decomposition, to establish the H-
electrochemical
potential difference inside and outside the sac, and thus promote ATP generation.
(ii) the composition and function of photolysome electron conveyor
below, the nature and function of several electron conveyor are described in the order of electronic transmission in the "Z" diagram.
1.PSII. Complex PSII.'s physiological function is to absorb light energy, carry out photochemical reactions, produce strong oxidants, make water cracking to interpret the release of oxygen, and transfer electrons from water to the mass of pyridone.
(1) PSII. The composition of the PSII. complex and the electron transfer PSII in the reaction center are protein complexes containing multi-sub-base. It consists of a spotlight pigment complex II., a central antenna, a reaction center, an oxygenation complex, a cytochrome, and a variety of cofactors. PSII.'s Spotlight Pigment complex, LHCII., is known as the "far-side antenna" because it is far from the reaction center. In addition to absorbing and transmitting light energy, LHCII. also has the function of dissipation of excessive excitation energy to protect the photocancer from the damage of bright light. In addition, LHCII.phosphate can be moved on the cystic membrane, from the stacked substring (rich in PSII.) region laterally to the non-stacked substring (rich in PSI.) region, and become PSI.'s spotlight pigment system, expanding PSI.'s catch area and coordinating the energy distribution between the two light systems. This is called "antenna movement".
CP47 and CP43, which make up the central antenna, refer to the polymer pigment protein complex with a molecular weight of 47,000, 43,000 and binding to chlorophyte, which is called a central antenna or a "near-side antenna" that delivers absorbed light energy to the PSII. reaction center faster than LHCII.
core of the PSII. reaction center is D1 and D2 peptides with molecular weights of 32,000 and 34,000
,
. The secondary electron feeder YZ, the central pigment P680, the primary electron subject Pheo, the secondary electron subject
QA
, QB, etc. are all combined on D1 and D2. The prosumal quinone binding to D1 is named QB, and the body glyph binding to D2 is named QA. Q here has a dual meaning, both as the head of quinone and as the head of the fluorescent annihilator (quencher). QA is a single electron transfer body, each reaction only accepts an electron-generated semiquinone, its electrons are re-transmitted to QB, QB is a dual electron transfer body, QB can twice receive electrons from QA and from the surrounding medium to accept 2 H-plus and restore to hydroquinone QH2. The resulting hydroquinone can be exchanged with the PQ of the library to generate PQH2.
oxygen-evolving complex, also known as M, is involved in the lysing of water and the release of oxygen on the side of PSII. near the cystic cavity.
(2) the oxidation reaction of water and oxygenated water is a unique reaction of plant photodegeneration in the biological world, and is also one of the most important reactions in photochemical use. It was mentioned earlier that for each release of 1 O2, 4 e-s need to be removed from 2 H2Os and 4 H-pluss formed at the same time.
1960s, P. Joliot of France invented a polar spectral electrode that sensitively measures changes in trace amounts of oxygen, using it to measure the photosynthelic oxygenation of chocal algae. They pre-positioned the glotoms in the dark and then gave them a series of instant flashes (e.g. 5 to 10 s per flash, 300ms apart). It is found that the yield of oxygen after the flash is not equal, is 4 as the cycle oscillation, that is, after the first flash there is no release of O2, the second release of a small amount of O2, the third release of O2 reached a peak, every 4 flashes appear 1 oxygen peak. The same results were obtained from the experiment of higher plant serrogens.
the fact that B. Kok (1970) et al. proposed a "four quantum-rational hypothesis" about H2O fissure-free oxygen," :(1) PSII. There is a positive charge between the reaction center and the H2O storage (S) (2) each flash, and S is handed over to PSII.reaction center 1 e-;(3) When S loses 4e- with 4 positive charges can crack 2 H2O release 1 O2, figure S is M, according to the degree of oxidation (i.e. how much positive charge) from low to high order, the different states of M are called S0, S1, S2, S3 and S4. That is, S0 without charge, S1 with 1 positive charge,...... S4 with 4 positive charges. Each flash pushes state S one step forward until S4. S4 then gets 4 e-s from 2 H2Os and returns to S0. This model is called a water oxidation clock or a Kok clock. The model also believes that S0 and S1 are stable states, with S2 and S3 secretly retreating to S1 and S4 unstable. Thus, after the dark adaptation process of the leafy body, 3/4 of M is in S1 and 1/4 is in S0. Therefore, the maximum amount of O2 is released at the third flash.
states of S are likely to represent different oxidation states containing manganese proteins. Each M contains 4 Mns, which can have a variety of different oxidizing states of M2, Mn3, and Mn4. All 4 Mns are required for the release of O2.
the original Kok clock model did not indicate the release site and the structure of H-plus. The flash experiments showed that when S changed, the number of releases of H-plus was 1, 0, 1, 2, i.e. 4H-plus in 2 H2O, which was released when S0→S1, S2→S3, S3→S4 changed. O2 in water is released, and H-plus enters the cystic cavity, increasing the concentration of H-plus in the sac cavity.
2.
, also known as pyrethromone, is the end electron subject of the PSII. reaction center and the electron transfer between the PSII. complex and the Cyt b6/f complex. The proteasome is a fat-soluble molecule that moves freely through the cystic membrane and transports electrons and protons. The content of pyrethlor in the membrane is very high, about 5% to 10% of the number of curlyin molecules, so it is called "PQ library".
PQ library as a buffer bank of electrons and protons, can balance the electron transmission between two optical systems (e.g. when one optical system is damaged, so that the electronic transmission of another optical system can still be carried out), can make multiple PSII. complexes and multiple Cyt b6/f complexes in contact, so that the electronics on the cystic membrane into a network. On the other hand, psython is a bielectronic, dual proton transfer body, oxidized python can receive electrons from PSII. (also PSI.) on the outside of the membrane, and bind to H-plus; This plays an important role in establishing proton gradients inside and outside the cystic membrane.
3.Cyt b6/f complex Cyt b6/f complex as an intermediate electronic carrier system connecting PSII. and PSI. Two optical systems, containing Cyt f, Cyt b6 (2, for electron transfer circulators) and Rieske iron The sulphur protein (also known as Fe-S) R, a non-hemoglobin Fe
protein
found by Rieske, mainly catalyses the oxidation of PQH2 and pc reduction, and transfers protons across the membrane from the outer interstate of the cystic membrane to the membrane cavity. So the Cyt b6/f complex is also known as PQH2. PC oxygen also enzyme.
PQH2+2PC(Cu2+) PQ + 2PC(Cu+) + 2H+ (4-20)
。 4. Plastocyanin (PC) is a copper-containing protein located on the inside surface of the cystic membrane, which is oxidized in blue. It is an electron transfer member between the Cyt b6/f complex and PSI. Electrons are transmitted through redox changes in copper ions in proteins.
The higher plant PSI. complex has a non-stacked part of the sac, the PSII.complex has a stacked part, and Cyt b6/f is distributed more evenly in the membrane, so it is assumed that the PC transmits electrons by diffusing and moving through the cystic cavity.
5.PSI. complex PSI.'s physiological function is to absorb light energy, carry out photochemical reactions, produce strong reducing agents, used to restore NADP plus, to achieve PC to NADP plus electronic transmission.
PSI of high-level plants consists of a reaction center and an LHCI. The reaction center contains 11 to 12 peptides, of which 1a and 1b are combined with P700 and A0, A1, FX, FA, FB and other electron conveyor. FX, FA, FB are PSI. 3 ferrothion proteins, all have 4 iron-4 sulfur center structure, of which 4 sulfur and protein 4 cysteine residues connected, they are mainly based on the 4 iron-4 sulfur center of iron ion oxidation also originally transmitted electrons. Each PSI. complex of higher plants contains two LHCI. (light harvesting pigment complex I.), and the light energy absorbed by LHCI. is transmitted to the reaction center of PSI.
。