Prof. Todd D. Porter

My laboratory is interested in the regulation and activity of enzymes involved in cholesterol synthesis. We use recombinant DNA techniques to express and characterize these enzymes and associated proteins in E. coli. We also use cultured hepatoma cells to evaluate the roles, and regulation, of these enzymes under more physiological conditions. We are particularly interested in how their activity is regulated at the protein level by regulatory proteins (kinases and accessory protein factors) as well as how sterols and botanical products can modulate their activity. Current studies are directed at understanding how green and black tea extracts, as well a policosanol (a mixture of very long straight-chain alcohols) inhibit cholesterol synthesis. General areas of interest include structure-function relationships of proteins, nutritional biochemistry, and molecular toxicology.

Biochemistry of the cytochrome P450 system, with emphasis on the structure and function of NADPH-cytochrome P450 reductase, the electron donor protein for this system, as well as the role of cytochrome b5 in this system.

Mice that lack hepatic cytochrome P450 reductase (POR)expression develop fatty livers, consisting predominantly of triglycerides. It is not clear why loss of POR expression would cause this lipidosis, as a role for POR in triglyceride synthesis and processing has not been discovered. POR is involved in both the synthesis and degradation of cholesterol, and so the connection may lie in disruption of this lipid homeostasis. We have replicated this lipidosis in hepatoma cell culture using an siRNA approach, facilitating investigation into this interesting and unexpected observation.

Ames mutagenicity assays with CYP2E1 and P450 reductase expressed in Salmonella tester strains.