(n.) A substance, in the form of reddish brown, microscopic, prismatic crystals, formed from dried blood by the action of strong acetic acid and common salt; -- called also Teichmann's crystals. Chemically, it is a hydrochloride of hematin.
Example Sentences:
(1) The appearance of an abundant class of polyribosomes was correlated with globin synthesis by demonstrating that a discrete class of polyribosomes arises in cells treated with the inducers hexamethylene bisacetamide and hemin.
(2) Finding (d) indicates that steps involved in the restorative effect of these compounds may not contribute to the stimulation of the globin synthesis in hemin-deficient lysates.
(3) The destabilization of the red cell membrane skeleton in the presence of crude iHCR is caused by release of hemin, which lowers the stability of membrane skeleton by weakening the spectrin-protein 4.1-actin interaction.
(4) Hemin failed to increase P450 levels previously depressed by TPA indicating that TPA acts by lowering apocytochrome levels.
(5) Prior exposure of the adherent cell layer to high concentrations of hemin (10 microM) was found to have a beneficial effect on the support of newly seeded cultures; however, the effect of lower hemin concentrations (0.1-1 microM) on stromal cell layer formation was not significant.
(6) Hemin increased satellite cell fusion by 27%, but decreased cell proliferative rate by 30%.
(7) Inhibition of hemin-mediated O2 activation by bovine superoxide dismutase and the copper tetrammine complex has been examined.
(8) Upon incubation of the HCI preparation with hemin (5-10 microM), the eIF-2 alpha kinase is converted into an inactive form and appears to become associated with related peptides forming high molecular weight complexes which can be reversibly activated by 2-mercaptoethanol.
(9) When the prorepressor is converted to the hemin-controlled translational repressor, either by prolonged warming in the absence of hemin or by incubation with N-ethylmaleimide for 5 min, and then incubated briefly with [gamma-32P]-ATP and Mg2+, a protein that migrates as a 100 000 molecular weight component on sodium dodecyl sulfate-polyacrylamide gels becomes phosphorylated.
(10) Its activity is independent of cyclic AMP as well as of the calcium-dependent regulator protein and is inhibited by hemin.
(11) The spin-labeled hemins were recombined with apoproteins of hemoglobin (Hb), myoglobin (Mb), cytochrome c peroxidase (EC 1.11.1.5) and horseradish peroxidase (EC 1.11.1.7).
(12) A model compound with similar optical properties to the CO-ligated protein can be prepared in dimethyl sulfoxide from hemin chloride, imidazole, and CO using chromous acetate as the heme reductant.
(13) Porphyromonas gingivalis is capable of in vitro growth when iron sources are either complexed to hemin or host iron transport proteins, or exist in an inorganic form.
(14) An assumption is advanced that the P. vitale catalase contains two hemin groups located in two protein subunits.
(15) The effect of hemin administration on the level of hepatic delta-amino-levulinate synthase mRNA was also examined.
(16) We were not able to detect any reaction between the radical (see article) and the hemin group (which would result in a complex such as heme O-2).
(17) The N-acetylimidazole-reacted apoprotein supplemented with hemin and reacted with hydroperoxides, neither showed electronic absorption spectra of higher oxidation states nor an EPR doublet signal due to a tyrosyl radical.
(18) With iron porphyrins (hemin, heme and their complexes) the charge of the iron and the nature of axial ligands determine the position and intensity of the O-bands in the MOR spectrum.
(19) Since S. typhimurium LT2 is not able to incorporate hemin, the identification of the mutants not stimulated by Delta-ALA was made on the basis of the simultaneous loss of catalase activity and cytochromes.
(20) Hemin, known to inactivate IRF in vivo, showed a similar, reversible effect in vitro, presumably by oxidizing IRF.
Protohemin
Definition:
Example Sentences:
(1) On the other hand, the irreversibility at alkaline pH was largely attributable to the modification of protohemin.
(2) The fact that protohemin-XIV, but not protohemin-I, exhibits a reversed orientation as a reconstitution intermediate provides direct evidence that vinyl contacts, as well as propionate links, modulate the relative stabilities of the initial encounter complexes between hemin and apomyoglobin.
(3) The chemical composition of Coprinus peroxidase showed 381 amino acid residues, 1 glucosamine, 3 true sugars, 3 calcium, and 1 non-heme iron other than 1 protohemin.
(4) Binding of protohemin completely inhibits reductase activity.
(5) In the recombination reaction with the azido complex of deuterohemin, the alpha subunit of the apohemoglobin preferentially combines with the hemin in the "disordered" heme orientation, whereas protohemin is inserted in either of two heme orientations.
(6) Addition of protoporphyrin IX or protohemin IX to the culture medium restored the respiratory activity of this mutant during growth at 35 C. The activities of various enzymes, including succinate-2,6-dichlorophenol indophenol (DCPIP), reduced nicotinamide adenine dinucleotide (NADH(2))-DCPIP, succinate-cytochrome c, and NADH(2)-cytochrome c oxidoreductase, and cytochrome oxidase, and the cytochrome c content of cells cultured in various conditions were determined.
(7) Protohemins-XI, -XIV both exhibited two species after reconstitution, with one disappearing with time.
(8) The splitting process of protohemin from holoperoxidase as followed by the change in the absorption spectrum at high temperatures coincided with the degrease in the activity, and it was found to be at least biphasic.
(9) The protohemin-III and -XIII isomers, with true 2-fold symmetry, yielded only homogeneous products.
(10) Apoperoxidase was more resistnat to heat denaturation but the modification or degradation of protohemin in heated enzyme was greater at alkaline pH than at acidic pH.
(11) The pyridine-ferrohemochrome spectrum of peroxidase exhibited slight shifts of the maxima of the alpha-band to shorter wavelength on heat treatment, and the paper chromatogram showed the presence of a new derivative other than protohemin.
(12) Inactivation of the peroxidase occurred at temperatures higher than 60degrees and involved three processes, i.e., dissociation of protohemin from the holoperoxidase, a conformation change in the apperoxidase, and the modification or degradation of protohemin.
(13) With the aid of two kinds of spin-labeled protohemins, the nature of the heme-protein interaction of various hemoproteins was investigated.
(14) Addition of NaN3 to ferric protohemin biscoordinated with 1-methylimidazole (1-MeIm) or 2-methylimidazole (2-MeIm) in (CH3)2SO resulted in sizeable visible absorption changes, corresponding to the formation of the mixed ligand complexes, hemin X N-3 X 1-MeIm and hemin X N-3 X 2-MeIm.
(15) The EPR spectrum was also changed strikingly upon the addition of protohemin.
(16) For protohemin-XI, the propionates were found in the unexpected positions of the 7-propionate and 2-vinyl groups of native myoglobin, indicating that propionates can occupy positions well within the hydrophobic interior.
(17) Spectrophotometric titration of spin-labeled globin with protohemin showed that 1 mol of globin (on the tetramer basis) combines with 4 mol of hemin, producing a holomethemoglobin spectrophotometrically indistinguishable from native methemoglobin.
(18) The NMR spectral comparison of paramagnetically shifted resonances with those of the well characterized horseradish peroxidase C, HRP(C), isoenzyme indicates that both cucumber peroxidases have a protohemin IX prosthetic group with proximal histidine coordinated to the heme iron.
(19) The alternate heme orientation for the metastable intermediates detected for protohemin-XI and -XIV involved rotational isomerism about the alpha,gamma-meso axes bisecting the vinyl positions, but these two axes are at right angles to each other in the protein matrix.
(20) The large differences in relative stability of the two orientations of native protohemin in the two cytochromes b5 is shown to result from the additivity of localized effects for the bovine protein and the near cancellation of competing effects in the rat protein.