Comparison of the performance of optical systems in fiber links 4000 km long

Matera, F.; Settembre, M.

doi:10.1080/01468039508241768

Cited by 6 publications

(1 citation statement)

References 21 publications

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“…41,[57][58][59][60][61] In the enzyme heme oxygenase (HO), iron(III) meso-hydroxy-isoporphyrin may be a key intermediate in the degradation of heme proteins to biliverdin, carbon monoxide, and free iron and thus is important to iron homeostasis and metabolism. 58,[60][61][62][63][64][65][66] Isoporphyrin-like intermediates have also been found to be catalytically active in bacterial denitrification pathways, specifically hydroxylamine oxidation to nitric oxide via hydroxylamine oxidoreductases (HAOs) or to nitrous oxide via cytochrome P460. 41,45,47,48,67 In HAOs, the active heme moiety is cross-linked to a nearby tyrosine residue at both the meso position and a pyrrole carbon (Figure S2A), while in cytochrome P460 the heme is cross-linked to a nearby Lys residue (Figure 2B).…”

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confidence: 99%

Formation and Reactivity of New Isoporphyrins: Implications for Understanding the Tyr-His Cross-Link Cofactor Biogenesis in Cytochrome c Oxidase

et al. 2019

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Cytochrome c oxidase (CcO) catalyzes the reduction of dioxygen to water utilizing a heterobinuclear active site composed of a heme moiety and a mononuclear copper center coordinated to three histidine residues, one of which is covalently cross-linked to a tyrosine residue via a post-translational modification (PTM). Although this tyrosine-histidine moiety has functional and structural importance, the pathway behind this net oxidative C-N bond coupling is still unknown. A novel route employing an iron(III) meso-substituted isoporphyrin derivative, isoelectronic with Cmpd-I ((Por •+ )Fe IV =O), is for the first time proposed to be a key intermediate in the Tyr-His cofactor biogenesis. Newly synthesized iron(III) meso-substituted isoporphyrins were prepared with azide, cyanide, and substituted imidazole functionalities, by adding nucleophiles to an iron(III) π-dication species formed via addition of trifluoroacetic acid to F 8 Cmpd-I (F 8 = (tetrakis(2,6-difluorophenyl)porphyrinate)). Isoporphyrin derivatives were characterized at cryogenic temperatures via ESI-MS and UV-vis, 2 H NMR, and EPR spectroscopies. Addition of 1,3,5-trimethoxybenzene or 4-methoxyphenol to the imidazolesubstituted isoporphyrin led to formation of the organic product containing the imidazole coupled to aromatic substrate via a new C-N bond, as detected via cryo-ESI-MS. Experimental evidence for the formation of an imidazole-substituted isoporphyrin and its promising reactivity to form the imidazole-phenol coupled product yields viability to the herein proposed pathway behind the PTM (i.e., biogenesis) leading to the key covalent Tyr-His cross-link in CcO.

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