The nonequilibrium structures of organometallic complexes acting as the active centers of enzymes

Summary

It has thus been shown that the reduction of heme-containing proteins does in fact pass through two main stages, the first of which does not require significant conformation rearrangement. This means that the rearrangement of the environment may take place after the electron reaches the appropriate orbital of the active center. The kinetic stabilization method has made it possible to detect the thermodynamically nonequilibrium intermediate states and in one case (adrenodoxin) to follow their subsequent relaxation in detail. In the case of hemoglobin it is possible to detect the low-spin reduced state, which has not been observed before. It may be assumed that the nonequilibrium states and the structural relaxation play an important role not only in proteins, but also in other reactions in the condensed phase. There are grounds for assuming that the proposed method of recording intermediate states will prove useful for the investigation of the mechanism of these processes. It should also be noted that by converting the active center from the oxidized to the reduced form without change in the structure of the environment it has been possible to reach a number of new conclusions regarding the structure of the equilibrium oxidized states. This technique may be of some methodological importance.