Vectorial aspects, electron

We next reconsider the vectorial aspects of proton and electron flow (Figs. 5-19 and 6-5) and examine the associated energetics. We will discuss the structures involved in the coupling of ATP formation to proton flow. We will also consider the stoichiometry of the various flows with respect to the ATP and NADPH requirements of CO2 fixation. 

In this chapter we emphasize energetic aspects and these are scalar quantities. If we want to understand more about reaction directionality then we need to examine vectorial aspects, which are treated in Chapter 10. In this chapter we treat the dynamics by classical mechanics. When we want to understand coherence effects we need to examine quantal superposition of states. We pick up on this theme from Chapter 7 onwards. There we will also extend the discussion to reactions that do not necessarily proceed for reactants in their ground electronic state. 

An important aspect of the function of photosynthetic complexes is their asymmetric arrangement in respect to the membrane and to the external and internal phases of the cellular compartments. This arrangement allows the catalysis of vectorial electron transfer and the performance of electrical work by promoting charge separation across the membrane dielectric barrier. It allows also in some cases the net translocation of protons across the membrane. These two processes are at the basis of the mechanism of energy conservation in photosynthesis coupled to the formation of ATP, which is added, in oxygenic photosynthesis, to the conservation of redox energy in the form of reduced pyridine nucleotide coenzymes. 

Because of the cylindrical symmetry of the total electric field in the column plasma, in two-term approximation the expansion of the velocity distribution can be represented by the expression f U,v/v,r) = 2n) mg/2f [fQ(U,r)+f U,r)v /v+f.(U,r)v,/v]. This expansion includes, in addition to the isotropic distribution fo(U, r), a radial component fr(U, r) and an axial component f (U,r) of the vectorial anisotropic part of the velocity distribution. In particular, this radial distribution component allows the particle and energy current density of the electrons in the radial direction to be described and thus reveals significant aspects of the electron confinement by the radial... 

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