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Melanins solubility

Tyrosine (Tyr or Y) (4-hydroxyphenylalanine ((5)-2-amino-3-(4-hydroxyphenyl)-propanoic acid)) is a polar, neutral, aromatic amino acid with the formula H00CCH(NH2)CH2C6H50H and is the precursor of thyroxin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and the pigment melanin. Being the precursor amino acid for the thyroid gland hormone thyroxin, a defect in this may result in hypothyroidism. Tyr is extremely soluble in water, a property that has proven useful in isolating this amino acid from protein hydrolysates. The occurrence of tyrosine- 0-sulfate as a constituent of human urine and fibrinogen has been reported. ... [Pg.674]

Melanins are classified according to their chemical structure into the insoluble black eumelanins (poly-5,6-indole quinones) and the alkali-soluble red phaeomelanins (polydihydrobenzothiazines). Nicolaus (5) includes another group, the homoaromatic phenolic allomelanins (per-... [Pg.254]

Gel permeation chromatography has been used in studies of water-soluble melanins. Several fractions were separated from allomelanin from Aspergillus niger on Sephadex G gels (Ref. 7, p. 131). Similarly, humic acids were separated into three fractions on Sephadex G-75 (297). [Pg.280]

The relatively poor solubility of natural and synthetic eumelanins (Table IV) is a considerable obstacle in structural determination. The rate of particle sedimentation in aqueous suspensions of synthetic melanins is... [Pg.280]

From a chemical point of view, and in a very simplified way, in the animal kingdom the so-called eumelanins (or melanins tout-court), black or dark brown, and completely insoluble in water, differ from pheomelanins, that contain sulfur, varying from yellow to brown-red, and alkali-soluble. Both the kinds of melanin can be present at the same time within the same organism. For a deeper insight in melanin occurrence and properties, see [238],... [Pg.1018]

Azino-bis-(3-ethylthiazoline-6-sulfonic acid) Plasma soluble melanin... [Pg.1020]

The melanin of sepia is found in the ink sac of cuttlefish. Aristotle in his book Historia Animalia mentioned that instead of intestines molluscs have an organ known as the mytin where a black substance is found which is especially abundant in cutdefish they put forth this black substance when frightened, particularly the cuttlefish . The ink has considerable staining power, and is alkaline and odorless. When fresh it disperses readily in water and is partly soluble in alkali, but insoluble in acid. This biological function of melanin appears to be defensive but the mechanism is uncertain (270). However, like other pigments, melanin can be utilized for camouflage purposes in insects and fishes. [Pg.150]

The species variability, unknown molecular weights, and poor solubility in most solvents of the melanins present difficulties in the choice and preparation of the material for titration. In the conductimetric study cited melanin was prepared according to Piatelli and Nicolaus substituting frozen Japanese squid (cuttlefish) for the Mediteranean sepia species used by the Italian authors. A sample of human melanin from Japanese hair was made available by Bolt, who used a new and mild procedure for extraction and purification. The natural melanins varied in their solubility in suitable solvents. Melanin derived from human liver melanoma appeared to be the least polymeric and most readily soluble. For squid melanin DM SO was used as the solvent, although some insoluble residue was left. DMSO, however, is not a truly inert solvent, but interacts with melanin, particularly at high temperatures. To minimize this reaction all tests were carried out in cold saturated solutions of melanin in DMSO, or suitable dilutions thereof. Triethanolamine completely dissolved human hair melanin and was employed in a series of tests. This solvent also... [Pg.522]

All Natural Melanin Powder, All Natural Melanin Water Soluble. See Melanin DL-allo-lsoleucine. See DL-lsoleucine Allomaleic acid. See Fumaric acid Allomaleic acid dimethyl ester. See Dimethyl fumarate... [Pg.155]

Manuf/Distrib. Arch Personal Care Prods. http //www.archchemicals.com, Barnet Prods. Genzyme http //www.genzyme.com, Inchema Lipo http //www.lipochemicais.com MeL-Co Sigma Thomley http //www.thornleycompany. com Trade Name Synonyms All Natural Melanin Powder t[MeL-Co] All Natural Melanin Water Soluble t[MeL-Co] Lipo Melanin 10% [Lipo http //www.lipochemicals.com], Melanink Powder t[MeL-Co] Melanink Suspension [MeL-Co]... [Pg.2516]

All Natural Melanin Powder All Natural Melanin Water Soluble Lipo Melanin 10%... [Pg.6276]

See other pages where Melanins solubility is mentioned: [Pg.115]    [Pg.59]    [Pg.286]    [Pg.98]    [Pg.58]    [Pg.566]    [Pg.116]    [Pg.188]    [Pg.50]    [Pg.242]    [Pg.659]    [Pg.256]    [Pg.280]    [Pg.297]    [Pg.121]    [Pg.275]    [Pg.227]    [Pg.565]    [Pg.911]    [Pg.1019]    [Pg.254]    [Pg.184]    [Pg.7]    [Pg.314]    [Pg.451]    [Pg.675]    [Pg.133]    [Pg.134]    [Pg.84]    [Pg.5]    [Pg.247]    [Pg.681]    [Pg.529]    [Pg.392]   
See also in sourсe #XX -- [ Pg.280 ]



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