Iron is an essential element for most organisms However, free iron and heme, its complex with protoporphyrin IX, can be extremely cytotoxic, due to the production of reactive oxygen species, eventually leading to oxidative stress. Thus, eukaryotic cells control iron availability by regulating its transport, storage and excretion as well as the biosynthesis and degradation of heme. In the genome...

Heme (iron-protoporphyrin IX) is an essential co-factor involved in multiple biological processes: oxygen transport and storage, electron transfer, drug and steroid metabolism, signal transduction, and micro RNA processing. However, excess free-heme is highly toxic due to its ability to promote oxidative stress and lipid peroxidation, thus leading to membrane injury and, ultimately, apoptosis. ...

Heme oxygenase-1 (HO-1) is an enzyme which catalyzes the rate-limiting step in heme degradation resulting in the formation of iron, carbon monoxide and biliverdin, which is subsequently converted to bilirubin by biliverdin reductase. The biological effects exerted by the products of this enzymatic reaction have gained much attention. The anti-oxidant, anti-inflammatory and cytoprotective functi...

The effects of various metalloporphyrins on hepatic heme oxygenase (EC 1.14.99.3) activity were examined in order to identify compounds that could inhibit heme degradation to bile pigment and might therefore be utilized to suppress the development of hyperbilirubinemia in the newborn. Among nine metal-protoporphyrin IX chelates (i.e., metal-hemes) studied, Sn-heme, Mn-heme, and Zn-heme substant...

Heme, the major functional form of iron, is synthesized in the mitochondria. Although disturbed heme metabolism causes mitochondrial decay, oxidative stress, and iron accumulation, all of which are hallmarks of ageing, heme has been little studied in nutritional deficiency, in ageing, or age-related disorders such as Alzheimer's disease (AD). Biosynthesis of heme requires Vitamin B(6), riboflav...

Background: Malaria parasites detoxify copious amounts of heme during human infection but enzyme involvement remains unclear. Results: Parasite-infected and uninfected erythrocytes contain indistinguishable low levels of heme catabolites, and a heme oxygenase-like parasite protein binds but does not degrade heme. Conclusion: P. falciparum parasites do not enzymatically degrade heme. Significanc...

Carbon monoxide (CO) is a pollutant commonly recognized for its toxicological attributes, including CNS and cardiovascular effects. But CO is also formed endogenously in mammalian tissues. Endogenously formed CO normally arises from heme degradation in a reaction catalyzed by heme oxygenase. While inhibitors of endogenous CO production can raise arterial pressure, heme loading can enhance CO pr...

In a previous study, we constructed a prototype thermally tolerant artificial peroxidase from an electron transfer protein, cytochrome c(552) from Thermus thermophilus, and demonstrated that engineering of proteins from thermophiles could be a promising methodology to produce artificial enzymes for practical use. In the present study, further improvement of the prototype (the V49D/M69A mutant) ...

Heme released from heme-binding proteins on internal hemorrhage, hemolysis, myolysis, or other cell damage is highly toxic due to oxidative and proinflammatory effects. Complex formation with hemopexin, the high-affinity heme-binding protein in plasma and cerebrospinal fluid, dampens these effects and is suggested to facilitate cellular heme metabolism. Using a ligand-affinity approach, we puri...