Research Interests
Project 1 – Organization and Complex Formation among Multiple Cytochrome P450 Enzymes in the Endoplasmic Reticulum – Cytochrome P450 enzymes are responsible for the metabolism of virtually every foreign compound that enters an organism. The major function of the P450 system is to carry out oxidation reactions, usually by hydroxylation of the substrate. Most of these reactions lead to products/intermediates that are more water-soluble and consequently more rapidly excreted. However, some products are reactive, capable of binding to biological macromolecules, an initial step leading to carcinogenesis.
P450 enzymes do not act independently, but require formation of a 1:1 complex with the flavoprotein NADPH-P450 reductase (reductase), which transfers electrons to P450. Because P450 exists in a large excess over reductase in vivo, the P450 enzymes must effectively compete for the reductase or be metabolically silent. The goal of this project is to examine the organization of multiple P450 enzymes and NADPH-cytochrome P450 reductase in the membrane, and to determine the potential for the formation of P450-P450 complexes that can influence the function of these enzymes. The studies include characterization of these interactions, identification of the contact points among the proteins, and determination of their effects on metabolism of hydrocarbons, carcinogens, and other foreign compounds.
Project 2 – How do Heme Oxygenase, Cytochrome P450 their Electron Transfer Partners Interact in the Endoplasmic Reticulum – Heme oxygenase (HO) has been reported to play a complex role in both cytoprotection and carcinogenesis. HO catalyzes the breakdown of heme to biliverdin, iron, and carbon monoxide (CO). HO also uses NADPH-P450 reductase as its source of electrons, suggesting that both P450 and HO may compete for the reductase in order to function. The interactions among these proteins could affect the initial mutations that lead to cancer through the P450 system, or could modulate protection of the cell through the heme oxygenase system. Because the full length form is unstable, most studies with HO have used a form where the membrane binding region of the protein is missing. Unfortunately, this does not allow HO to associate with the membrane as occurs in vivo. We recently generated a stable form of HO that is able to bind to the membrane. The goal of these experiments is to better understand how reductase, P450 and HO-1 interact within a membrane environment. This will be accomplished by measuring the catalytic effectiveness of each of these proteins both separately and in combination.
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Contact: wbacke@lsuhsc.edu