The Department of Biomedicine

BBB seminar: Milagros Medina

Protein-protein interactions in electron transfer systems. The mechanism of action of ferredoxin-NADP+ reductase

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Milagros Medina
Departamento de Bioquímica y Biología Molecular y Celular, University of Zaragoza, Spain

Although the understanding of protein function and, more specifically, of the role of the individual amino acid residues involved in substrate binding and in the catalytic action, have achieved considerable progress, we are still far from knowing all the parameters in those processes. Among the most relevant proteins studied are those involved in electron transfer processes due to their practical interest. Moreover, the opportunity to design novel enzymatic systems and proteins is becoming more feasible, especially due to the increased detailed knowledge of the three-dimensional structure of many proteins. As a first step in this direction recent investigations have been aimed to redesign already existing systems and proteins. Taking all this into account, we aim to increase the knowledge of the parameters that maintain the electron transfer reactions in proteins of electron transfer chains. Thus, we are individually studying and also combining two biological electron transfer chains that are involved in the production of biological compounds of important economical value: the photosynthetic electron transport chain involved in the NADPH production and the CytP450 chain that catalyses steroid hormones synthesis in adrenal glands. Thus, in a first approach our work is aimed to determine the parameters that control the interaction between ferredoxin (or flavodoxin) and both ferredoxin-NADP+ reductase (FNR) and photosystem I. Additionally, a hybrid chain combining these proteins with those catalyzing the synthesis of steroid hormones is being produced.

Milagros Medina

Dr. Milagros Medina´s research interest focuses on the study of the mechanisms involved in the electron transfer in proteins, studying mainly the mechanism of electron transfer from photosystem I to NADP+ to produce NADPH in photosynthetic organisms. Such system has been analysed in detail by the group at the University of Zaragoza were she has been belonging to for the last 15 years. Thus, different spectroscopic and kinetic techniques have been applied to the study of the protein-protein and protein-substrate interaction, as well as of the electron transfer itself, and structures of these proteins have been obtained either individually or in functional complexes. Since two of the proteins involved in this electron transfer system are flavoproteins, this group has also produced a valuable contribution to the study of the mechanism of electron and hydride transfer in flavoproteins. Recently, the interest of the group is also focusing on the design of flavoproteins with modified flavin properties and of hybrid electron transfer chains between the photosynthetic one and those producing steroid hormones. Dr. Medina has published more than 60 papers in this area.

Homepage: http://www.bioquz.es/bioquimica/