STUDIES ON PROTEIN ELECTRON CARRIER COMPLEXES: ADRENODOXIN REDUCTASE- ADRENODOXIN COMPLEX IN STEROID BIOSYNTHESIS

摘要

Electron-transfer reactions are characteristic features of a variety of fundamental biological processes that include energy metabolism, hormone biosynthesis and xenobiotic detoxification. For the proteins, involved in these processes, the active site is comprised of a metal center (most frequently Fe) as well as of organic cofactors (flavins, quinones). The great interest directed towards understanding of the biological electron-transfer processes in recent years reflects the importance of metabolic processes in which electron transfer is involved. At an electron-transfer protein study, the relative positions of the electron donor and electron acceptor sites at the time of electron transfer have to be determined. To study electron-transfer reactions between the donor and acceptor centers located in different protein molecules, a solution containing the two proteins of interest is prepared at conditions optimal for their complex formation. The electron transfer from one to the other protein within the formed complex can be considered as unimolecular. The most important structural factors in determining the electronic coupling between the donor and acceptor centers in any case are the distance and the protein structure between them. The main problems of research in electron transfer are: Whether the nature of the protein structure matters, or only the distance separating these sites? Which structural elements of proteins may or may not facilitate the electronic coupling of the centers, and thereby influence the rate of electron transfer? A special question arises on the role of aromatic groups in coupling of the donor and acceptor centers.