The inducible form of Heme Oxygenase-1 (HO-1), a major endoplasmic reticulum (ER) associated heme protein, is known to play important roles in protection against oxidative and chemical stress by degrading free heme released from degradation of heme proteins. In this study we show that induced expression of HO-1 by subjecting macrophage RAW-264.7 cells to chemical or physiological hypoxia result...

Heme oxygenase (HO) plays a critical role in attenuating the production of reactive oxygen species through its ability to degrade heme in an enzymatic process that leads to the production of equimolar amounts of carbon monoxide and biliverdin/bilirubin and the release of free iron. The present review examines the beneficial role of HO-1 (inducible form of HO) that is achieved by increased expre...

The hmuO gene is required for the utilization of heme and hemoglobin as iron sources by Corynebacterium diphtheriae. The product of hmuO has homology to eukaryotic heme oxygenases which are involved in the degradation of heme and the release of iron. To investigate the mechanism of hmuO regulation, a promoterless lacZ gene present on the promoter-probe vector pCM502 was placed under transcripti...

Heme plays critical roles in erythropoiesis not only as a structural component of hemoglobin but also as a regulator of erythroid proliferation by affecting the expression of proteins involved in iron transport and globin synthesis. Within the cell, heme is synthesized in the mitochondria and is subsequently transported to the cytosol for incorporation into hemoglobin and other hemoproteins. Be...

The regulated turnover of endoplasmic reticulum (ER)-resident membrane proteins requires their extraction from the membrane lipid bilayer and subsequent proteasome-mediated degradation. Cleavage within the transmembrane domain provides an attractive mechanism to facilitate protein dislocation but has never been shown for endogenous substrates. To determine whether intramembrane proteolysis, spe...

Studies with synthetic metal-porphyrin complexes in which the central iron atom of heme is replaced by other elements indicate that those heme analogues that cannot be enzymatically degraded to bile pigments possess novel biological properties that may have considerable clinical as well as experimental value. Such studies have revealed the important role that the central metal atom plays in det...

Heme oxygenase (HO), in conjunction with biliverdin reductase, degrades heme to carbon monoxide, ferrous iron and bilirubin (BR); the latter is a potent antioxidant. The induced isoform HO-1 has evoked intense research interest, especially because it manifests anti-inflammatory and anti-apoptotic effects relieving acute cell stress. The mechanisms by which HO mediates the described effects are ...

Human indoleamine 2,3-dioxygenase (hIDO), a monomeric heme enzyme, catalyzes the oxidative degradation of L-Trp and other indoleamine derivatives. Using Fourier transform infrared and optical absorption spectroscopy, we have investigated the interplay between ferrous hIDO, the ligand analog CO, and the physiological substrate L-Trp. These data provide the long sought evidence for two distinct L...

BACKGROUND Delayed cerebral vasospasm is the most common cause of mortality and severe neurological impairment in patients who survive subarachnoid hemorrhage. Despite improvements in the field of diagnostic imaging, options for prevention and medical treatment-primarily with the calcium channel antagonist nimodipine or hemodynamic manipulations-are insufficient. Previous studies have suggested...

Hmu O, a heme degradation enzyme in the pathogen Corynebacterium diphtheriae, catalyzes the oxygen-dependent conversion of hemin to biliverdin, carbon monoxide, and free iron. A bacterial expression system using a synthetic gene coding for the 215-amino acid, full-length Hmu O has been constructed. Expressed at very high levels in Escherichia coli BL21, the enzyme binds hemin stoichiometrically...