The structure of neuromelanin and its iron binding site studied by infrared spectroscopy

Bridelli, Maria Grazia; Tampellini, Davide; Zecca, Luigi

doi:10.1016/s0014-5793(99)01001-7

Cited by 77 publications

(87 citation statements)

References 21 publications

(26 reference statements)

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“…5) and fit well with established vibrations in the literature (27)(28)(29)(30). A broad band corresponding to phenolic OH stretches is seen at 3400 cm Ϫ1 , aromatic CϭC stretches and COO stretches are visible at 1600 -1650 cm…”

Section: Resultssupporting

confidence: 87%

Melanin and Glycera Jaws

Moses

Harreld

Stucky

et al. 2006

Journal of Biological Chemistry

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Section: Resultssupporting

confidence: 87%

Melanin and Glycera Jaws

Moses

Harreld

Stucky

et al. 2006

Journal of Biological Chemistry

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“…Aluminum and iron ions can bind with DOPA and its derivative to yield chelate complexes quickly. 28,34,35,58,59 The spectrum of iron-DOPA complex shows the maxima at 435 -442 nm and 660 -700 nm, 28 which is also observed in Fig. 1.…”

Section: +supporting

confidence: 61%

Aluminum Facilitation of the Iron-Mediated Oxidation of DOPA to Melanin

2004

ANAL. SCI.

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Aluminum, a trivalent cation unable to undergo redox reactions, is shown to faciliate iron-initiated DOPA oxidation in the melanin pathway under acidic condition of pH 5.5, which is a favored medium for aluminum facilitation of iron-induced lipid peroxidation. In the process of oxidation of DOPA to melanin in the presence of the metal ions, Fe 3+ and H2O2 oxidize DOPA to dopachrome (DC), then Al 3+ catalyzes the conversion of DC to 5,6-dihydroxyindole (DHI) and finally Fe 3+ oxidizes DHI to indole-5,6-quinone (IQ), which polymerizes immediately to melanochrome and melanin. The reactions involve the intermediate complexes of metal ions and DOPA or its derivative. The present results indicate that aluminum can enhance the oxidative stress on iron-mediated DOPA oxidation in melanin pathway under acidic condition through the cooperation of iron and aluminum ions.

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“…The presence of this nitro derivative indicates that horseradish peroxidase/H 2 O 2 can promote the nitrosation of dopamine. Under the conditions established for this investigation, the nucleophilic addition of NO or other RNI such as NO 2 Ϫ to oxidized derivatives of dopamine would most likely generate a noncyclized molecule such as 6-nitrosodopamine quinone (6NDAQ), or nitrosodopamine semiquinone (6NDASQ) (Fig. 11).…”

Section: Resultsmentioning

confidence: 99%

“…1 Neuronal degeneration in PD is accompanied by the progressive depletion of the neurotransmitter dopamine, as well as the pigment derived from its autoxidation, neuromelanin (1)(2)(3). Several mechanisms have been proposed to account for the selective vulnerability of the pigmented nigrostriatal dopaminergic neurons in PD, but the pathogenesis of this disease remains largely enigmatic.…”

mentioning

confidence: 99%

The Effects of Nitric Oxide on the Oxidations ofl-Dopa and Dopamine Mediated by Tyrosinase and Peroxidase

Nappi

Vass

2001

Journal of Biological Chemistry

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The effects of nitric oxide (NO) on both tyrosinase/O 2 -and horseradish peroxidase/H 2 O 2 -mediated oxidations of dopamine and its o-dihydric phenol precursor L-dopa were compared with autoxidative processes and quantitatively assessed by oxidative and reductive electrochemical detection systems. In peroxidase/H 2 O 2 /NO-catalyzed reactions, significantly more substrate was oxidized than in the corresponding control incubations lacking NO. In tyrosinase/O 2 /NO-promoted reactions the total amounts of L-dopa and dopamine oxidized were significantly less than the amounts of the substrates oxidized by enzyme alone. These data indicate that the activity of the heme protein peroxidase was enhanced by NO, whereas tyrosinase, a copper-containing monoxygenase, was inhibited. The NO-mediated reduction of tyrosinase/O 2 activity may be attributed to the formation of an inhibitory copper⅐nitrosyl complex. An oxidized nitrodopamine derivative, considered to be either the quinone or semiquinone of 6-nitrosodopamine, was generated in peroxidase/H 2 O 2 /NO-mediated reactions with dopamine along with two oxidized melanin precursors, dopamine quinone and dopaminechrome. No corresponding nitroso compound was formed in reactions involving L-dopa or in any of the tyrosinase-mediated reactions. The formation of such a noncyclized nitrosodopamine represents an important alternative pathway in catecholamine metabolism, one that by-passes the formation of cytoprotective indole precursors of melanin. The results of this investigation suggest that cellular integrity and function can be adversely affected by NO-promoted oxidations of dopamine and other catechols, reactions that not only accelerate their conversion to reactive quinones but also form potentially cytotoxic noncyclized nitroso derivatives. Reduced levels of dopamine in the brain through NO-enhanced oxidation of the catecholamine will almost certainly be manifested by diminished levels of the dopamine-derived brain pigment neuromelanin.The selective degeneration of melanized nigrostriatal dopaminergic neurons and attendant functional impairments of associated neuronal pathways are primary neuropathological manifestations of Parkinson's disease (PD).1 Neuronal degeneration in PD is accompanied by the progressive depletion of the neurotransmitter dopamine, as well as the pigment derived from its autoxidation, neuromelanin (1-3). Several mechanisms have been proposed to account for the selective vulnerability of the pigmented nigrostriatal dopaminergic neurons in PD, but the pathogenesis of this disease remains largely enigmatic. The neuropathology associated with PD has been attributed to oxidative stress resulting from the toxic effects of certain reactive intermediates of oxygen (ROI) (4), most notably the hydroxyl radical ( ⅐ OH), a highly reactive molecule generated by the interaction of hydrogen peroxide (H 2 O 2 ) with superoxide anion (O 2 . ), transition metals (Fe 2ϩ or Cu ϩ ), or nitric oxide (NO) (5, 6).The preferential targeting and destruction of nigrostriatal d...

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The structure of neuromelanin and its iron binding site studied by infrared spectroscopy

Cited by 77 publications

References 21 publications

Melanin and Glycera Jaws

Melanin and Glycera Jaws

Aluminum Facilitation of the Iron-Mediated Oxidation of DOPA to Melanin

The Effects of Nitric Oxide on the Oxidations ofl-Dopa and Dopamine Mediated by Tyrosinase and Peroxidase

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