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[en] Ellagic acid (EA) has been gaining a considerable attention in recent years. The interest in non-drug and herbal base therapies is being increased. EA is a biological molecule found in different fruits and seeds, which is known to have the ability to scavenge reactive oxygen radicals. It has been observed that methyl tert-butyl ether (MTBE) has destructive effects on structure and function of hemoglobin (Hb), an important respiratory blood protein. This conclusion is reached from our far-UV circular dichroism, Soret band absorption, fluorescence and oxygen affinity measurements. It has also been observed from our chemiluminscence measurements that ROS production is increased in the presence of MTBE which degrades heme in Hb. The main goal of this study was to offer a way to scavenge ROS produced during MTBE interaction with Hb. We report that EA decreased the heme degradation and ROS production in Hb solutions containing MTBE. - Highlights: • Hemoglobin structure and function were disturbed in the presence of methyl tert-butyl ether (MTBE). • Heme degradation was increased due to production of reactive oxygen specious. • Deleterious effects of reactive oxygen specious were reduced by ellagic acid.
[en] Recently, several members of a vertebrate protein family containing a six trans-membrane (6TM) domain and involved in apoptosis and cancer (e.g. STEAP, STAMP1, TSAP6), have been identified in Golgi and cytoplasmic membranes. The exact function of these proteins remains unknown. We related this 6TM domain to distant protein families using intermediate sequences and methods of iterative profile sequence similarity search. Here we show for the first time that this 6TM domain is homolog to the 6TM heme binding domain of both the NADPH oxidase (Nox) family and the YedZ family of bacterial oxidoreductases. This finding gives novel insights about the existence of a previously undetected electron transfer system involved in apoptosis and cancer, and suggests further steps in the experimental characterization of these evolutionarily related families
[en] In soybean previous studies enabled the identification of MAPK3 and 6 whose activity is enhanced within the signaling pathway leading to defense reactions. In this study the effects of different compounds related to hemeoxygenase (HO-1) biosynthesis on mitogen-activated protein kinase (MAPK’s) genes expression in soybean seeds were tested. To this end, 20μM hemine, 22μM ZnPPIX, 0.5mM furidine or 100μM 8-bromoguanosine 3',5'-cyclic monophosphate (8Br) were added to pre-hydrated seeds for 5 days. MAPK’s genes expression was enhanced in seeds treated with hemine. This result indicates that heme catabolism could be involved in the signaling mediated by this cascade pathway. To confirm this hypothesis experiments were carried out in the precsence of ZnPPIX, a potent irreversible HO-1 inhibitor. In this case, no gene induction was observed. On the other hand, 8Br, a cGMP analog, induced HO-1 gene expression but did not modulate MAPK’s, indicating that this effect could not be mediated by cGMP. When the action of furidine, an abscisic acid inhibitor, was tested a diminution of HO-1 gene expression was observed. In this regard, MAPK’s showed a different response, being MAPK6 the only transcript that showed a diminished respect to controls, while MAPK3 mRNA as well as MAPKK1 was enhanced. These results were confirmed by western blotting and activity determinations. (authors)
[en] Supramolecular anchoring of metalloporphyrins in a protein is an attractive approach to the generation of artificial enzymes. Here, we employ the hydrophobic nanocage of single-ring mutant of bacterial GroEL protein for this purpose. We found that multiple monomeric hemin cofactors can be efficiently loaded into the protein nanocage. The as-prepared biohybrid possessed an oxidase-like catalytic activity and followed the typical Michaelis–Menten kinetics and a ping-pong mechanism in the H2O2-mediated oxidation of model substrates. In comparison with natural peroxidase, the artificial enzyme exhibited higher affinity for the model substrate. A simple and sensitive colorimetric method for the quantitative detection of H2O2 and glucose was also developed based on the artificial enzyme, with the detection limits determined to be 3.0 μM for H2O2 and 5.0 μM for glucose, respectively. The protein nanocage-based artificial enzyme is very flexible and is envisioned to be adapted readily for binding other metal complexes and catalysis of other reactions.
[en] We examined the contribution of carbon monoxide (CO), an enzymatic product of heme oxygenase (HO), to methylmercury (MeHg) cytotoxicity in SH-SY5Y cells, because this gas molecule is reported to activate Nrf2, which plays a protective role against MeHg-mediated cell damage. Exposure of SH-SY5Y cells to CO gas resulted in protection against MeHg cytotoxicity, with activation of Nrf2. Interestingly, pretreatment with tin-protoporphyrin IX, a specific inhibitor of HO, caused a reduction in basal Nrf2 activity and thus enhanced sensitivity to MeHg. No induction of isoform 1 of HO (HO-1) was seen during MeHg exposure, but constitutive expression of isoform 2 (HO-2) occurred, suggesting that CO produced by HO-2 is the main participant in the protection against MeHg toxicity. Studies of small interfering RNA-mediated knockdown of HO-2 in the cells supported this possibility. Our results suggest that CO gas and its producing enzyme HO-2 are key molecules in cellular protection against MeHg, presumably through basal activation of Nrf2.
[en] Electron spin echo studies have been performed on the model compound for cytochrome a, bis imidazole heme a, and the results compared with those obtained for bis imidazole protoheme and for cytochrome a. The 14N coupling with the iron in the heme a model compound, as obtained from a study of the nuclear modulation effect, is comparable with that seen for the bis imidazole complex of protoheme. The magnetic field dependence of the linear electric field effect is essentially the same in both bis imidazole complexes, but is markedly different from that observed for cytochrome a. Thus the odd field component of the crystal field in bis imid heme a is different from that in cytochrome a. (author)
[en] Hemin was found to enhance the growth of murine erythroid colonies in culture. In the presence of 100 mU/ml erythropoietin (EPO), the addition of hemin (0.05-0.2 mM) resulted in the growth of twice as many colonies as were obtained with EPO alone. Hemin also significantly increased erythroid colony formation in culture in the absence of added EPO. Hemoblobin synthesis as measured by the incorporation of 59Fe into cyclohexanone extractable heme was augmented in culture by hemin. Neither Δ-aminolevulinic acid, a hemin precursor, nor FeCl3 increased colony number. (author)