Fe(III)-Coordination Properties of Neuromelanin Components:  5,6-Dihydroxyindole and 5,6-Dihydroxyindole-2-carboxylic Acid

Charkoudian, Louise K.; Franz, Katherine J.

doi:10.1021/ic060014r

Cited by 134 publications

(149 citation statements)

References 60 publications

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“…The pK a values for these groups are 4.25, 9.76, and 13.2, respectively. [11,20] This implies that at pH 2.5 and 3.0 the neutral state dominates, with ratios of neutral state to carboxylate anion of 98:2 and 95:5, respectively. Comparing these values with the observed reduction in fluorescence intensity on the short wavelength side of the spectrum by a factor of 3 on going from pH 3.0 to- wards 2.5 suggests that the band at l = 378 nm is owed to the carboxylate anion or a photoproduct of it.…”

Section: Resultsmentioning

confidence: 99%

UV‐Dissipation Mechanisms in the Eumelanin Building Block DHICA

Huijser¹,

Pezzella²,

Hannestad³

et al. 2010

ChemPhysChem

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The UV-dissipative mechanisms of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and the 4,7-dideutero derivative (DHICA-d(2)) in buffered H(2)O or D(2)O have been characterized by using ultrafast time-resolved fluorescence spectroscopy. Excitation of the carboxylate anion form, the dominating state at neutral pH, leads to dual fluorescence. The band peaking at lambda=378 nm is caused by emission from the excited initial geometry. The second band around lambda=450 nm is owed to a complex formed between the mono-anion and specific buffer components. In the absence of complex formation, the mono-anion solely decays non-radiatively or by emission with a lifetime of about 2.1 ns. Excitation of the neutral carboxylic acid state, which dominates at acidic pH, leads to a weak emission around lambda=427 nm with a short lifetime of 240 ps. This emission originates from the zwitterionic state, formed upon excitation of the neutral state by sub-ps excited-state intramolecular proton transfer (ESIPT) between the carboxylic acid group and the indole nitrogen. Future studies will unravel whether this also occurs in larger building blocks and ESIPT is a built-in photoprotective mechanism in epidermal eumelanin.

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Section: Resultsmentioning

confidence: 99%

UV‐Dissipation Mechanisms in the Eumelanin Building Block DHICA

Huijser¹,

Pezzella²,

Hannestad³

et al. 2010

ChemPhysChem

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“…For the synthesis of dopamine, Fe(II) is used as a co-factor by the enzyme tyrosine hydroxylase. Further, Fe(III) is capable of inducing OS by its interaction with neuromelanin (96) and may also be involved in the formation of asynuclein oligomers (192,396). In a recent study, Davies et al (119) showed that a-synucluein acts as a cellular ferrireductase, and thereby helps in reducing iron (III) to bio-available iron (II).…”

Section: E Role Of Iron In Neurodegenerationmentioning

confidence: 99%

Redox Proteomics in Selected Neurodegenerative Disorders: From Its Infancy to Future Applications

Butterfield

Perluigi

Reed

et al. 2012

Antioxidants & Redox Signaling

157

142

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Several studies demonstrated that oxidative damage is a characteristic feature of many neurodegenerative diseases. The accumulation of oxidatively modified proteins may disrupt cellular functions by affecting protein expression, protein turnover, cell signaling, and induction of apoptosis and necrosis, suggesting that protein oxidation could have both physiological and pathological significance. For nearly two decades, our laboratory focused particular attention on studying oxidative damage of proteins and how their chemical modifications induced by reactive oxygen species/reactive nitrogen species correlate with pathology, biochemical alterations, and clinical presentations of Alzheimer's disease. This comprehensive article outlines basic knowledge of oxidative modification of proteins and lipids, followed by the principles of redox proteomics analysis, which also involve recent advances of mass spectrometry technology, and its application to selected age-related neurodegenerative diseases. Redox proteomics results obtained in different diseases and animal models thereof may provide new insights into the main mechanisms involved in the pathogenesis and progression of oxidativestress-related neurodegenerative disorders. Redox proteomics can be considered a multifaceted approach that has the potential to provide insights into the molecular mechanisms of a disease, to find disease markers, as well as to identify potential targets for drug therapy. Considering the importance of a better understanding of the cause/effect of protein dysfunction in the pathogenesis and progression of neurodegenerative disorders, this article provides an overview of the intrinsic power of the redox proteomics approach together with the most significant results obtained by our laboratory and others during almost 10 years of research on neurodegenerative disorders since we initiated the field of redox proteomics. Antioxid. Redox Signal. 17, 1610-1655.

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“…Conditions for the analysis (electrolyte concentration, pH, detection potential) were optimized based on previous reports from the group [58,59]. As shown in Figure 6, cathodic migration (towards the waste reservoir) was observed for dopamine (pKa 1 = 8.9, pKa 2 = 9.6, pKa 3 = 12.0) [60,61] and 2-aminophenol (pKa 1 = 4.78, pKa 2 = 9.97) [62]. Catechol (pKa 1 = 9.3, pKa 2 = 13.3) [60,63], was neutral in the selected background electrolyte.…”

Section: Analytical Performance Of the Pmma Devicementioning

confidence: 99%

Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving

Gabriel,

Coltro,

Garcia

2014

Electrophoresis

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This paper describes the effects of different modes and engraving parameters on the dimensions of microfluidic structures produced in PMMA using laser engraving. The engraving modes included raster and vector while the explored engraving parameters included power, speed, frequency, resolution, line-width and number of passes. Under the optimum conditions, the technique was applied to produce channels suitable for CE separations. Taking advantage of the possibility to cut-through the substrates, the laser was also used to define solution reservoirs (buffer, sample, and waste) and a PDMS-based decoupler. The final device was used to perform the analysis of a model mixture of phenolic compounds within 200 s with baseline resolution.

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Fe(III)-Coordination Properties of Neuromelanin Components: 5,6-Dihydroxyindole and 5,6-Dihydroxyindole-2-carboxylic Acid

Cited by 134 publications

References 60 publications

UV‐Dissipation Mechanisms in the Eumelanin Building Block DHICA

UV‐Dissipation Mechanisms in the Eumelanin Building Block DHICA

Redox Proteomics in Selected Neurodegenerative Disorders: From Its Infancy to Future Applications

Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving

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