Breath. Oxidising fosforilirovanie

you are: Breath

Of considered above reactions molecular oxygen does not participate in one, and meanwhile, as it is known, oxygen consumption - the most characteristic line of process which we name breath. The requirement for oxygen arises because a considerable share of the energy which was earlier in geksoze, contains now in restored carriers NADH and FADH2 from which it should be liberated in the third stage of breath when these carriers will be oxidised again, having transferred the elektrony to free oxygen. As in the mentioned carriers (NADH and FADH2) it is concluded enough considerable quantity of energy to be liberated it should besides gradually, by transfer elektrona from these kofaktorov to variety of the carriers connected with fibers and definitely focused in space as a part of a chain of carrying over elektronov. Each such carrier is at a little lower level vosstanovlennosti, than its predecessor, and according to it contains less energy. As a final acceptor elektrona molecular oxygen which together with the proton which has arrived from the surrounding water environment, forms a new molecule of water serves:

The carrying over Chain elektronov consists of a number of carriers which can be either in restored, or in the oxidised condition (fig. 5.8). These carriers represent enzymes for which kofermentami various derivatives of vitamins serve. Carriers on an internal membrane mitohondry (fig. 2.19 and 5.6 see) just as are localised on tilakoidah hloroplastov carriers elektronov, operating at photosynthesis are located. Finish a carrying over chain elektronov gemsoderzhashchie tsitohromy in which arriving to them elektrony restore iron, translating it from okisnoj forms (Fe3 +) in zakisnuju (Fe2 +); from tsitohromov elektrony pass to oxygen. at several stages in a carrying over chain elektronov energy is liberated and used for synthesis ATR from ADP and inorganic phosphate. On each molecule NADH transferring elektrony in a chain of carrying over elektronov, are synthesised, as believe, three molecules ATR, and on each molecule FADH2 - two. as ATR it is formed as a result of oxidation of each previous carrier and elektrony eventually pass to oxygen, this process has received the name oxidising fosforilirovanija. Complexity of all these reactions does clear necessity of corresponding difficult structure mitohondry. Each enzyme should settle down so that it could accept a certain substratum and to transfer a ready product to following enzyme in the same to a number. Infringement in any point of a chain of carrying over elektronov completely blocks transport elektronov. It is known, for example, that such

Respiratory poisons as tsianid and okis carbon, carry out the action, incorporating to iron tsitohromov therefore there is impossible transition Fe3 + in Fe2 +. The cage thus can be lost, if in it there is no other way on which elektrony could be transferred on oxygen.

For breath, as well as for photosynthesis (see gl. 4), hemiosmoticheskaja the theory offers the harmonous explanation, allowing to understand how the energy received from carrying over elektronov on a chain of carriers, is interfaced to synthesis ATR (fig. 5.9). Carriers elektronov are located asymmetrically on an internal membrane mitohondrii. Some of them transfer not only elektrony, but also protons owing to what between two parties of an internal membrane mitohondrii there is a gradient of concentration of protons; business is here the same as and on a membrane tilakoidov, with that difference that protons are transported from within outside so from the inside mitohondrialnaja the membrane appears more alkaline, and with external - more sour. carrying over of each pair elektronov on a chain of carriers from NADH to 1/2О2приводит to transition through mitohondrialnuju a membrane of six ions N +. This considerable gradient rn between two parties of a membrane represents, as well as at photosynthesis, a potential energy source. The energy allocated at return movement of protons, i.e. At their moving in mitohondriju on special channels in gribovidnyh vyrostah (fig. 2.18 see), it is spent with the assistance of the interface factor for synthesis ATR from ADP and Р1.