Elucidating the Role of Biliverdin Reductase in the Expression of Heme Oxygenase-1 as a Cytoprotective Response to Stress

Many types of enzymes in living systems use hemin as a prosthetic group to catalyze oxidation/reduction reactions or for the binding/transport of reactive molecules (e.g. oxygen). For instance, several cytochromes of the mitochondrial electron transport chain are “heme” enzymes as are the major drug/xenobiotic-metabolizing enzymes of the endoplasmic reticulum, the cytochromes P450 (CYP or P450). The heme group of the P450s allows these enzymes to use redox chemistry to bind molecular oxygen and cleave the O-O bond, thus forming a reactive, high-valent oxygen species that can insert oxygen into otherwise stable carbon-hydrogen bonds of drugs/xenobiotics (White and Coon, 1980). The unfavorable thermodynamics of this type of reaction has caused the P450s to be likened to “catalytic blowtorches” (Schlichting et al., 2000), and the process is essential for the elimination and clearance of many lipophilic compounds ingested from the environment. Catalase is an important protective heme enzyme that is responsible for degrading N N