Co-polymerization of dopa and cysteinyldopa in melanogenesis in vitro

Ito, Shosuke; Novellino, Ettore; Chioccara, Francesco; Misuraca, Giovanna; Prota, Giuseppe

doi:10.1007/bf01978591

Cited by 65 publications

(23 citation statements)

References 8 publications

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“…DOPA in the oxidized quinone form can homocouple to form di-DOPA cross-links or undergo nucleophilic attack by lysine or cysteine residues.22 Evidence of cysteinyl-DOPA residues in the P. californica adhesive has been reported.9 The reddish-brown coloration of the cement that develops over several hours is also consistent with the presence of cysteinyl-DOPA-based pigments in the glue. 23 The spontaneous coupling between cysteine and DOPA would be accelerated at the elevated pH of seawater because the deprotonated thiol of cysteine is a stronger nucleophile than the protonated form. The quinone-based covalent crosslinking may continue for several hours and be responsible for the tough leathery consistency of the fully cured adhesive.…”

Section: Nanoscale Structurementioning

confidence: 99%

Multiscale Structure of the Underwater Adhesive ofPhragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient

et al. 2007

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Phragmatopoma Californica builds a tubular dwelling by gluing bits of sand and seashell together underwater with a proteinaceous adhesive. In the lab, the animals will build with 0.5 mm glass beads. Two spots of glue with a consistent volume of about 100 pL each are deposited on the glass beads before placement on the end of the tube. The animals wriggled the particles for 20-30 s before letting go, which suggested that the adhesive was sufficiently set within 30 s to support the glass beads. The structure of the adhesive joints was examined at the micro-and nanoscopic length scales using laser scanning confocal and atomic force microscopies. At the microscale, the adhesive was a cellular solid with cell diameters ranging from 0.5 to 6.0 μm, distributed to create a steep porosity gradient that ranged from near zero at the outside edges to about 50% at the center of the adhesive joint. At the nanoscale, the adhesive appeared to be an accretion of trillions of deformable nanospheres, reminiscent of a high-solids-content latex adhesive. The implications of the structure for the functionality of the adhesive is discussed.

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Section: Nanoscale Structurementioning

confidence: 99%

Multiscale Structure of the Underwater Adhesive ofPhragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient

et al. 2007

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“…The skin pigment melanin is a mixture of polymerized and oxidized DOPA and 5-S-cysteinyl-DOPA (Ito et al, 1980;Prota et al, 1976;Rorsman et al, 1979;Sealy et al, 1982). Tyrosinase oxidizes tyrosine to DOPA, but also, DOPA to DOPA-quinone.…”

Section: Introductionmentioning

confidence: 97%

The apparent autoxidation rate of catechols in dopamine-rich regions of human brains increases with the degree of depigmentation of substantia nigra

Fornstedt

Brun

Rosengren

et al. 1989

J Neural Transm Gen Sect

167

108

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The concentrations of the 5-S-cysteinyl adducts of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylalanine (DOPA) and the levels of noradrenaline (NA), DA, DOPAC and DOPA were determined in the putamen (PUT), caudate nucleus (CN) and substantia nigra (SN) of human post mortem brains with or without depigmentation and degeneration of the SN. The levels of DA, DOPAC and DOPA decreased with the degree of depigmentation and degeneration in the three brain regions while NA levels only decreased in SN and PUT. In general, the concentrations of the 5-S-cysteinyl adducts did not differ, but the ratios of 5-S-cysteinyl-DA/DA, 5-S-cysteinyl-DOPAC/DOPAC and 5-S-cysteinyl-DOPA/DOPA were higher in patients with a more depigmentated and degenerated SN, except for the 5-S-cysteinyl-DA/DA ratio in the PUT. Higher ratios were also found in the cell body areas compared to the neuron terminal areas. Thus depigmentation and degeneration of dopaminergic SN neurons, seem to be correlated to enhanced rates of autoxidation, possibly due to an impaired antioxidant capacity.

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“…Capture of thiols by DOPAquinone effectively shifts pigmentation from the synthesis of eumelanin to the production of pheomelanin and, therefore, represents a crucial control point in determining the type of melanin formed. This switch may be ultimately controlled by the availability of cysteine within melanosomes (Ito et al, 1980), thus highlighting the importance of transmembrane import of cysteine.…”

Section: Discussionmentioning

confidence: 99%

“…Many reports suggested a direct role of GSH in pheomelanogenesis (Benedetto et al, 1982;Ito et al, 1980;Prota, 1972Prota, , 1992. Experiments performed in test tubes, or using melanocyte extracts, showed that glutathionylDOPA, formed by the addition of GSH to DOPAquinone, can be produced, with subsequent conversion to cysteinylDOPA (It0 et al, 1985;Prota, 1992).…”

Section: Discussionmentioning

confidence: 99%

Cysteine Transport in Melanosomes from Murine Melanocytes

Potterf

Virador

Wakamatsu

et al. 1999

Pigment Cell Research

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The synthesis of pheomelanin requires the incorporation of thiol-containing compound(s) during the process of mammalian melanogenesis. Since melanins are produced only in specialized, membrane-bound organelles, known as melanosomes, such thiol donor(s) must cross the membrane barrier from the cytosol to the melanosome interior. Cysteine and/or glutathione (GSH) were proposed as suitable thiol donors, although uptake of these compounds into melanosomes was not previously characterized. In this study, we show that cysteine is transported, in a temperature- and concentration-dependent manner, across membranes of melanosomes derived from murine melanocytes. Additional proof that cysteine uptake results from a carrier-mediated process and is not due to simple diffusion or to a membrane channel, was obtained in countertransport experiments, in which melanosomes preloaded with cysteine methyl ester took up significantly more [35S]cysteine than did unloaded controls. In contrast, we were unable to detect any significant uptake of [35S]GSH over a wide concentration range, in the presence or in the absence of reducing agent. This study is the first demonstration of melanosomal membrane transport of cysteine, and it strongly suggests that free cysteine is the thiol source utilized for pheomelanin synthesis in mammalian melanocytes.

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Co-polymerization of dopa and cysteinyldopa in melanogenesis in vitro

Cited by 65 publications

References 8 publications

Multiscale Structure of the Underwater Adhesive ofPhragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient

Multiscale Structure of the Underwater Adhesive ofPhragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient

The apparent autoxidation rate of catechols in dopamine-rich regions of human brains increases with the degree of depigmentation of substantia nigra

Cysteine Transport in Melanosomes from Murine Melanocytes

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