Negentropy (i.e., order) is created locally in a system which is surrounded by an ocean of dissipative entropy production. Examples are found in the world of dead matter as well as in the biosphere (for reviews see Kondepudi and Prigogine 1998; Haken 2004). Life, being stable far from equilibrium, as already pointed out by Schrödinger (1944), can be understood in terms of dissipative structures as well. Doubtless, photosynthesis plays a key role for the occurrence of living order on earth. As proposed by Boltzmann, it is the negentropy stored in the photosynthetic products which maintain the structures of life. The photosynthetic membrane appears to be the

location at which the high and dissipative energy Galunisertib nmr through-put occurs, selleck chemicals llc and in which negentropy is created for terrestrial life. The radical pair formation is the first step of the process of order formation. The separation of charges as well as the organization of the electron spins lead to a transient high-order (i.e., low-entropy) state. Hence, photo-CIDEP can be considered as the first product of photosynthetic production of order. The solid-state photo-CIDNP effect might be considered

as part of this initial process of photosynthetic construction of order. Since the GSK461364 energies involved are marginally compared to the reaction energies, only kinetic effects of the spin-chemistry on the reaction yield could be considered.

In fact, various magnetic-field effects on plant growth have been observed experimentally (For reviews, see Belyavskaya 2004; Galland and Pazur 2005). On the other hand, one may argue that the solid-state photo-CIDNP effect as observed till now does not occur under natural conditions but requires high magnetic fields and cyclic electron transfer, which is reached, for example in RCs of Rb. sphaeroides by reduction or removal of Methane monooxygenase the quinones. Therefore, one may consider the solid-state photo-CIDNP effect as a by-process, occurring under artificial conditions, which is accidentally a very useful as an analytical tool for the electronic structure of the photochemical machinery of RCs. In any case, due to its limited size and complexity as well as due to its relevance, the order and dissipation processes of spins during the radical pair formation in photosynthetic RCs provide a stimulating target for irreversible thermodynamics of microscopic processes. Intrinsic property of RCs The list of RCs showing the solid-state photo-CIDNP effect is growing (Table 1). The list contains systems from various bacteria as well as from plants. In all natural RCs, in which we were able to induce cyclic ET, we observed the solid-state photo-CIDNP effect as well. It appears that the occurrence of the solid-state photo-CIDNP effect is an intrinsic property of photosynthetic RCs (Roy et al. 2008).