To probe the role of copper and protons in heme-copper oxidase (HCO), we have performed kinetic studies on an engineered heme-copper center in sperm whale myoglobin (Leu-29 --> HisPhe-43 --> His, called Cu(B)Mb) that closely mimics the heme-copper center in HCO. In the absence of metal ions, the engineered Cu(B) center in Cu(B)Mb decreases the O(2) binding affinity of the heme. However, additio...

DiGeorge syndrome critical region gene 8 (DGCR8) is the RNA-binding partner protein of the nuclease Drosha. DGCR8 and Drosha recognize and cleave primary transcripts of microRNAs (pri-miRNAs) in the maturation of canonical microRNAs (miRNAs) in animals. We previously reported that human, frog, and starfish DGCR8 bind heme when expressed in Escherichia coli and that Fe(III) heme activates apoDGC...

The effects of long-term administration of very large doses of Sn-protoporphyrin on hematological indices, histological changes, plasma bilirubin levels, tissue heme oxygenase activity, and activities of heme biosynthetic enzymes, were examined in genetically anemic mutant mice with hemolytic anemia (sphha/sphha). Long-term weekly treatment with Sn-protoporphyrin (100 mumol/kg body weight for 3...

Heme oxygenase (HO) 1 and HO-2 gene expressions are known to increase cellular antioxidant and antiinflammatory properties through activation of a battery of cytoprotective systems, including decreases in cyclooxygenase 1 and NADPH oxidase (NOX-2) and elevated levels of extracellular superoxide dismutase and NO. The heme-HO system (HO-1 and HO-2) acts as an endogenous antiinflammatory and prote...

Tin(IV)-protoporphyrin (Sn-protoporphyrin) potently inhibits heme degradation to bile pigments in vitro and in vivo, a property that confers upon this synthetic compound the ability to suppress a variety of experimentally induced and naturally occurring forms of jaundice in animals and humans. Utilizing rat liver heme oxygenase purified to homogeneity together with appropriate immunoquantitatio...

Heme oxygenase (HO) 1 and HO-2 gene expressions are known to increase cellular antioxidant and antiinflammatory properties through activation of a battery of cytoprotective systems, including decreases in cyclooxygenase 1 and NADPH oxidase (NOX-2) and elevated levels of extracellular superoxide dismutase and NO. The heme-HO system (HO-1 and HO-2) acts as an endogenous antiinflammatory and prote...

Dehaloperoxidase (DHP) from the terebellid polychaete, Amphitrite ornata, is the first hemoglobin that has peroxidase activity as part of its native function. The substrate 2,4,6-tribromophenol (TBP) is oxidatively debrominated by DHP to form 2,6-dibromoquinone (DBQ) in a two-electron process. There is a well-defined internal binding site for TBP above the heme, a feature not observed in other ...

Chemically induced rat bepatocyte nodules and carcinomas have a reduced capacity to oxidize drugs. The reduction in monooxygenase activity results largely from the partial loss of cytochrome P-450, a hemecontaining terminal electron acceptor. To determine whether the cyto chrome P-450 deficit was indicative of an altered heme metabolism, we quantitated four heme-containing proteins in normal ra...