Dinitrosyl iron complexes in biological systems

Formation of dinitrosyl iron complexes (DNIC), with the general formula Fe(NO)2(L)2, was observed in many species of plants, animals and bacteria. They are important in human physiology and pathology, including inflammatory states, Parkinson disease, and malignancy. The report presents in detail the electron and steric structure of DNIC, electron paramagnetic resonance (EPR) spectroscopy and infrared spectra. Further, biological functions of DNIC are discussed and their generation in the animal cell, with emphasis on the nature of ligands and the origin of iron. On the basis of other authors data and own experimental results it has been demonstrated that the labile iron pool is not the only source of iron participating in DNIC formation in vivo, however, it has an important role in DNIC biosynthesis, probably by stimulating the release of iron centers of ferroproteins. Also, it has been shown that DNIC are formed in animal cells with high molecular mass proteins (>100 kDa) as ligands, whereas iron release form ferroproteins in the course of DNIC formation is the cause of increase in DNA damage; on the other hand, DNIC-DNA interactions are unspecific and have an ionic character. (authors)