Showing papers on "Protoporphyrins published in 2007"
TL;DR: The roles of the recently identified heme/porphyrin transport proteins heme carrier protein 1 (HCP1), FLVCR, Abcg2 and Abcb6 are discussed and how these transporters contribute to intracellular heme and porphyrin homeostasis are discussed.
224 citations
TL;DR: It is proposed that the targets are the heme binding proteins in the pathways (CcmC, CcmE, and CcmF for system I and CcsA for system II) and Surprisingly, Zn and Sn protoporphyrins are potent inhibitors of the pathways, and exogenous heme competes with this inhibition.
Abstract: Studies have indicated that specific heme delivery to apocytochrome c is a critical feature of the cytochrome c biogenesis pathways called system I and II. To determine directly the heme requirements of each system, including whether other metal porphyrins can be incorporated into cytochromes c, we engineered Escherichia coli so that the natural system I (ccmABCDEFGH) was deleted and exogenous porphyrins were the sole source of porphyrins (ΔhemA). The engineered E. coli strains that produced recombinant system I (from E. coli) or system II (from Helicobacter) facilitated studies of the heme concentration dependence of each system. Using this exogenous porphyrin approach, it was shown that in system I the levels of heme used are at least fivefold lower than the levels used in system II, providing an important advantage for system I. Neither system could assemble holocytochromes c with other metal porphyrins, suggesting that the attachment mechanism is specific for Fe protoporphyrin. Surprisingly, Zn and Sn protoporphyrins are potent inhibitors of the pathways, and exogenous heme competes with this inhibition. We propose that the targets are the heme binding proteins in the pathways (CcmC, CcmE, and CcmF for system I and CcsA for system II).
42 citations
TL;DR: In this article, the metal-exchange reaction of Cadmium deuteroporphyrin and cadmium gematoporphrin with cobalt chloride in acetonitrile is studied spectrophotometrically.
Abstract: The metal-exchange reaction of cadmium deuteroporphyrin (CdDP) and cadmium gematoporphyrin (CdGP) with cobalt chloride in acetonitrile is studied spectrophotometrically. The stoichiometry of the metal-exchange reaction is determined. The results are compared with the exchange reaction of cadmium mesoporphyrin and cadmium protoporphyrin with cobalt acetate in acetonitrile. Substituents in the 2,4-positions of cadmium complexes of protoporphyrins are shown to influence the rate of the metal-exchange reaction. The increasing order of the rates of the metal-exchange reaction between protoporphyrins and cobalt chloride in acetonitrile is established.
7 citations
TL;DR: In this paper, spectropotentiometric titration and direct calorimetry were used to study the thermodynamics of protonation of protoporphyrins in acetonitrile and dimethyl sulfoxide.
Abstract: Spectropotentiometric titration and direct calorimetry were used to study the thermodynamics of protonation of protoporphyrins in acetonitrile and dimethyl sulfoxide. Comparative analysis of the resulting data was performed.
1 citations