The iron-regulated surface determinants (Isd) of Staphylococcus aureus, including surface proteins IsdA, IsdB, IsdC, and IsdH and ATP-binding cassette transporter IsdDEF, constitute the machinery for acquiring heme as a preferred iron source. Here we report hemin transfer from hemin-containing IsdA (holo-IsdA) to hemin-free IsdC (apo-IsdC). The reaction has an equilibrium constant of 10 +/- 5 a...

Porphyromonas gingivalis is a Gram-negative black pigmenting anaerobe that is unable to synthesize heme [Fe(II)-protoporphyrin IX] or hemin [Fe(III)-protoporphyrin IX-Cl], which are important growth/virulence factors, and must therefore derive them from the host. Porphyromonas gingivalis expresses several proteinaceous hemin-binding sites, which are important in the binding/transport of heme/he...

a sensitive and fast chemiluminescence (cl) method has been described for the direct determination of atropine. the method is based on the quenching effect of atropine on the cl signals of the luminol– h2o2 reaction catalyzed by hemin in an alkaline medium. hemin could strongly enhance the chemiluminescence of the luminol–h2o2 system. the luminophor of the luminol–h2o2–hemin cl system was ident...

Exogenous addition of hemin to glucose-repressed cells of Saccharomyces cerevisiae restores the level of Iso-1-cytochrome C messengers to that observed in derepressed cells. In vitro transcription in isolated nuclei has shown a 4-fold stimulation in the synthesis of Iso-1-cytochrome C messengers in repressed but hemin-treated and derepressed cells compared to the repressed cells. Studies on in ...

Exploring long-range electron transport across protein assemblies is a central interest in both the fundamental research of biological processes and the emerging field of bioelectronics. This work examines the use of serum-albumin-based freestanding mats as macroscopic electron mediators in bioelectronic devices. In particular, this study focuses on how doping the protein mat with hemin improve...

Protohemin and covalently bound hemin were determined in eight aerobic bacterial strains. A good correlation between protohemin content and luminol reactivity was found. The ratio of luminol reaction to protohemin for the eight investigated strains was essentially identical to that of pure protohemin, 0.7 X 10(16) mV/mol. Covalently bound hemin contributed to the chemiluminescence to a minor ex...

Soft-x-ray absorption spectroscopy at the L_{2,3} edge of the iron center in bovine hemoglobin and hemin under physiological conditions is reported for the first time. Spectra of the same compounds in solid form are presented for comparison. Striking differences in the electronic structure of the metalloporphyrin are observed between the liquid and solid compounds. We unambiguously show that he...

Porphyromonas gingivalis is a periopathogen strongly associated with the development of adult-type periodontitis. Both the virulence characteristics of periopathogens and host-related factors are believed to contribute to periodontitis. P. gingivalis lipopolysaccharide (LPS) displays a significant amount of lipid A structural heterogeneity, containing both penta- and tetra-acylated lipid A stru...

Cadmium (Cd) contamination harms plant growth and human health. The application of hemin (ferroprotoporphyrin IX) can effectively relieve abiotic stresses in plants. This work investigates the effects on alleviating Cd toxicity enhancing tolerance maize seedlings. In this study, seedlings were cultivated nutrient solutions, with a combination CdCl2 (464 ?mol L?1) (100 L?1). We measured status, ...

The human leukemia K562 cell line can be induced by 20 micro M hemin to reversibly accumulate embryonic and fetal hemoglobins without any change in the rate of cell division. When we reduced the rate of cell division by glutamine starvation or addition of hydroxyurea, the cells increased by tenfold the basal hemoglobin level of 0.3-0.5 pg Hb/cell. The combined effects of hemin and inhibitors of...