Universiẗat, Diss., 2003--Frankfurt (Main).

This Ph.D. thesis addresses the structural characterization of the unique family of tetrameric flavoproteins WrbA, the role of which in the life of cells is still largely unknown but its enzymatic activity and expression properties implicate it in the cell protection against oxidative stress. Proteins of the WrbA family were proved to carry out two-electron reductions of quinones and in this way to prevent generation of the free radicals, similarly to other flavoproteins known as quinone oxidoreductases. Crystal structures of the liganded and unliganded forms of the prototypical WrbA from Escherichia coli were determined. Comparative analyses of these structures with the related flavoproteins were intended to identify and explain the defining structural features of the WrbA family and to clarify its structural and functional relationships to the other flavoproteins.