The heme oxygenase system was reconstituted from a heme oxygenase preparation highly purified from pig spleen microsomes and a partially purified NADPHcytochrome c reductase from pig liver microsomes. In the reconstituted heme oxygenase reaction, the relationship between the rate of heme degradation and the heme concentration was sigmoidal, and the heme concentration which gave the half-maximum...

Heme oxygenase (HO) converts heme to carbon monoxide (CO) and biliverdin, which is metabolized rapidly to bilirubin. CO is implicated as an intercellular messenger, whereas bilirubin could function as an antioxidant. These cellular functions differ significantly from those of HO in peripheral tissues, in which it degrades heme from senescent erythrocytes, suggesting that the regulation of HO ma...

Heme-oxygenase-1 (HO-1), the rate-limiting enzyme of heme degradation, has powerful anti-oxidant properties related to the production of the reactive oxygen species scavenger bilirubin. However, some data suggest that HO-1 could also inhibit the cellular production of reactive oxygen species. Therefore, we investigated whether the anti-oxidant properties of HO-1 could be mediated by modulation ...

The synthetic metalloporphyrin, Cr-protoporphyrin, as a potent competitive inhibitor of heme oxygenase activity in rat spleen, liver, and kidney. When administered to neonatal animals in a single dose immediately after birth, Cr-protoporphyrin suppresses postnatal hyperbilirubinemia and produces a marked and sustained lowering of heme oxidation activity in liver, spleen, and kidney. The metallo...

Haem a and cytochrome c were isotopically labelled in mitochondria from rat heart and liver after injection of delta-amino[2,3-(3)H(2)]laevulate, a specific haem precursor. [guanido-(14)C]Arginine or l-[4,5-(3)H(2)]leucine were used to label mitochondrial proteins. Half-lives were measured from biological decay in vivo and were similar (5.5-6.2 days) for haem a, cytochrome c and [(14)C]arginine...

NADPH-cytochrome P450 oxidoreductase (CPR) supplies electrons to various heme proteins including heme oxygenase (HO), which is a key enzyme for heme degradation. Electrons from NADPH flow first to flavin adenine dinucleotide, then to flavin mononucleotide (FMN), and finally to heme in the redox partner. For electron transfer from CPR to its redox partner, the ''closed-open transition'' of CPR i...