Hemin Research Articles

Cloning and functional characterization of Neisseria gonorrhoeae tonB, exbB and exbD genes.

Neisseria gonorrhoeae is able to utilize iron (Fe) from a variety of sources including transferrin (TF) and lactoferrin (LF). To gain insight into the molecular mechanisms used by gonococci to scavenge Fe from TF and LF, we cloned a 3.5 kb segment of wild-type DNA that repaired the defect in tlu mutants, which are unable to take up Fe from either TF or LF despite exhibiting apparently normal ligand binding to the receptor. Nucleotide sequence determination identified three open reading frames (ORFs), designated ORF1, ORF2, and ORF3, which were arranged in tandem. The deduced amino acid sequence of the 852 bp ORF1 encoded a 28 kDa protein that exhibited 26-32% identity with TonB proteins of nine other bacteria. The 663 bp ORF2 predicted a 24 kDa protein and the 435 bp long ORF3 predicted a 15 kDa protein. These predicted protein sequences exhibited 32-38% and 24-36% identity, respectively, with ExbB and ExbD proteins of three other bacteria. Thus, the sequence comparison identified the ORF1, ORF2 and ORF3 as gonococcal homologues of the E. coli tonB, exbB and exbD genes. An insertional mutation in the tonB homologue resulted in the failure of gonococci to grow with TF, LF or human haemoglobin (HB) as sole Fe sources and in the inability to take up 55Fe from TF and LF. The tonB mutation did not prevent the utilization of Fe from citrate (CT) or haemin (HM). Binding of TF, LF and HB to whole cells in a solid-phase binding assay was largely unaffected by the tonB mutation. We conclude that the pathways for utilization of Fe bound to TF, LF and HB but not to HM or CT were dependent on the TonB system.

Mechanisms of hemin catalyzed oxidations

Mechanisms of hemin catalyzed oxidations

Viability of Vacuum-Dried Urediniospores of Melampsora Lini Maintained Over Three Decades

(1985). Viability of Vacuum-Dried Urediniospores of Melampsora Lini Maintained Over Three Decades. Mycologia: Vol. 77, No. 3, pp. 491-493.

Inhibition by hemin of dinitropyrene-induced mutagenesis in Chinese hamster V79 cells.

The inhibitory effects of hemin on the mutagenic activities of 1,3-, 1,6- and 1,8-dinitropyrenes (1,3-,1,6- and 1,8-DNPs) were investigated in Chinese hamster V79 cells. Mutant cells were selected on the basis of their resistance to ouabain. Hemin itself did not have any cytotoxic effect on Chinese hamster V79 cells, and did not induce mutations when added at a concentration of 10 micrograms/ml. The mutagenic activities of 1,3-, 1,6- and 1,8-DNPs were inhibited dose-dependently by hemin and were reduced 91.7%, 95.7% and 94.7%, respectively, by the highest concentration of hemin tested (10 micrograms/ml).

A Simplified Medium for Growth and Sporulation ofPilobolusSpecies

(1976). A Simplified Medium for Growth and Sporulation of Pilobolus Species. Mycologia: Vol. 68, No. 6, pp. 1254-1258.

Hemin as a catalyst for chemiluminescence

Hemin as a catalyst for chemiluminescence

Hemin dialkylphosphate compounds

Hemin dialkylphosphate compounds

Studies on Erythrocyte Hemins. V

Studies on Erythrocyte Hemins. V

Dimeric nature of hemin hydroxides

Dimeric nature of hemin hydroxides

Studies on Erythrocyte Hemins. II

Studies on Erythrocyte Hemins. II

Studies on Erythrocyte Hemins. III

Studies on Erythrocyte Hemins. III

Studies on Erythrocyte Hemins. IV

Studies on Erythrocyte Hemins. IV

Studies on Erythrocyte Hemins. I.

Studies on Erythrocyte Hemins. I.

Stimulation of hemin synthesis in Ehrlich ascites tumor cells by mouse liver RNA.

Les cellules ascites de la tumeur Ehrlich couvaient in vitro avec le precurseur radioactif de l'hemineδ-aminolevulinic acid-4-C14. Les preparations de ARN du foie de la souris stimulaient le niveau de synthese de l'hemine.

COMBINATION OF GLOBIN AND IT'S DERIVATIVES WITH HEMINS AND PORPHYRINS.

COMBINATION OF GLOBIN AND IT'S DERIVATIVES WITH HEMINS AND PORPHYRINS.

LIQUID SCINTILLATION COUNTING OF C14-LABELED HEMOGLOBIN AND HEMIN BY A MODIFIED SCHOENIGER TECHNIQUE.

Abstract A rapid, reproducible method for radioassay of C 14 -labeled hemoglobin and hemin is described. This modification of the Schoniger technique permits multiple determinations without the use of internal standards. The radioassay of compounds bearing multiple isotopic labels is examined. Suggestions are made for the proper spectral separation of various isotopes in this counting system.

PARTITION CHROMATOGRAPHY OF HEMINS. SEPARATION OF THE PROSTHETIC GROUPS OF CYTOCHROMES a AND a3

PARTITION CHROMATOGRAPHY OF HEMINS. SEPARATION OF THE PROSTHETIC GROUPS OF CYTOCHROMES a AND a3

Studies on Plant Catalase

Catalase activity is observed in almost all kind of plant material as far as it has been investigated.The amount of catalase, however, is very low and the extracted enzyme solution very unstable, compared with that of animals.From these reasons, the plant catalase has not yet been crystallized.Now, we have succeeded in crystallizing the catalase extracted from both spinach and rice-plant leaves, by the application of the butanol-treatment to extract this from chloroplasts.The crystal obtained has the same absorption spectrum as that of animal, and therefore it seems that plant catalase also has haemin as its prosthetic group.Judging from their optimum temperatures, the protein part of both catalases seem to differ and each have a suitable optimum temperature in order to make its enzyme activity the highest in the circumstance where it grows.

FURTHER STUDIES ON THE BIOSYNTHESIS OF HEMIN IN BONE MARROW PREPARATIONS

FURTHER STUDIES ON THE BIOSYNTHESIS OF HEMIN IN BONE MARROW PREPARATIONS

Hemin as a growth factor for certain isoniazid-resistant strains of Mycobacterium tuberculosis.

Hemin as a growth factor for certain isoniazid-resistant strains of Mycobacterium tuberculosis.