- Acetyl radical production by the methylglyoxal-peroxynitrite system: A possible route for l-lysine acetylation
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Methylglyoxal is an α-oxoaldehyde putatively produced in excess from triose phosphates, aminoacetone, and acetone in some disorders, particularly in diabetes. Here, we investigate the nucleophilic addition of ONOO-, known as a potent oxidant and nucleophile, to methylglyoxal, yielding an acetyl radical intermediate and ultimately formate and acetate ions. The rate of ONOO- decay in the presence of methylglyoxal [k2,app = (1.0 ± 0.1) × 103 M-1 s-1; k 2 ≈ 1.0 × 105 M-1 s-1] at pH 7.2 and 25 °C was found to be faster than that reported with monocarbonyl substrates (k2 3 M-1 s-1), diacetyl (k2 = 1.0 × 104 M-1 s -1), or CO2 (k2 = 3-6 × 104 M-1 s-1). The pH profile of the methylglyoxal- peroxynitrite reaction describes an ascendant curve with an inflection around pH 7.2, which roughly coincides with the pKa values of both ONOOH and H2PO4- ion. Electron paramagnetic resonance spin trapping experiments with 2-methyl-2-nitrosopropane revealed concentration-dependent formation of an adduct that can be attributed to 2-methyl-2-nitrosopropane-CH3CO? (aN = 0.83 mT). Spin trapping with 3,5-dibromo-4-nitrosobenzene sulfonate gave a signal that could be assigned to a methyl radical adduct [aN = 1.41 mT; aH = 1.35 mT; aH(m) = 0.08 mT]. The 2-methyl-2-nitrosopropane-CH 3CO? adduct could also be observed by replacement of ONOO - with H2O2, although at much lower yields. Acetyl radicals could be also trapped by added l-lysine as indicated by the presence of εN-acetyl-l-lysine in the spent reaction mixture. This raises the hypothesis that ONOO-/H2O2 in the presence of methylglyoxal is endowed with the potential to acetylate proteins in post-translational processes.
- Massari, Julio,Tokikawa, Rita,Zanolli, Luiz,Tavares, Marina Franco Maggi,Assuncao, Nilson Antonio,Bechara, Etelvino Jose Henriques
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- Preparation method of Nalpha-[(9H-fluorene-9-ylmethoxy)carbonyl]-Nepsilon-acetyl-L-lysine
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The invention discloses a preparation method of Nalpha-[(9H-fluoren-9-ylmethoxy)carbonyl]-Nepsilon-acetyl-L-lysine. The preparation method is mainly used for solving the technical problems of complexity, long cycle, low yield, high cost and the like in an original process. The preparation method provided by the invention comprises the following steps: 1, lysine hydrochloride and copper salt reactto form a lysine-copper complex; 2, the lysine-copper complex and an acetyl donor react to prepare an Nepsilon-acetyl-L-lysine-copper complex; 3, the Nepsilon-acetyl-L-lysine-copper complex is subjected to copper removal to obtain an Nepsilon-acetyl-L-lysine aqueous solution; and 4, the Nepsilon-acetyl-L-lysine aqueous solution and a protective agent of fmoc-group are mixed, in the presence of anorganic solvent, a pH value is adjusted to 8-9 through an alkali compound sodium carbonate aqueous solution, reaction is carried out, and thus Nalpha-[(9H-fluorene-9-ylmethoxy)carbonyl]-Nepsilon-acetyl-L-lysine is prepared. The preparation method provided by the invention adopts a reasonable process route to prepare the Nalpha-[(9H-fluorene-9-ylmethoxy)carbonyl]-Nepsilon-acetyl-L-lysine, so that the preparation method is suitable for mass production.
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Paragraph 0026-0028
(2019/02/10)
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- Peptide Tyrosinase Activators
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Peptides that increase melanin synthesis are provided. These peptides include pentapeptides YSSWY, YRSRK, and their variants. The peptides may activate the enzymatic activity of tyrosinase to increase melanin synthesis. The pharmaceutical, cosmetic, and other compositions including the peptides are also provided. The methods of increasing melanin production in epidermis of a subject are provided where the methods include administering compositions comprising an amount of one or more peptides effective to increase the melanin production. The methods also include treating vitiligo or other hypopigmentation disorders with compositions including one or more peptides.
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- Decomposition of copper-amino acid complexes by oxalic acid dihydrate
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A facile approach to the synthesis of some side-chain-protected amino acids via oxalic acid dihydrate as the copper sequestering reagent is presented. The copper in the amino acid complex reacted with oxalic acid dihydrate to form insoluble cupric oxalate, with the free amino acid released. Compared with conventional methods, this method is convenient, inexpensive, and environmentally friendly.
- Liu, Yi,Jia, Genguang,Ling, Xin,Lan, Nuo,Zheng, Youguang,Li, Sai,Zhang, Ling,Liu, Ling,Zhang, Rongli,Xue, Yunsheng
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experimental part
p. 557 - 559
(2012/08/08)
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- Degradation of 1-deoxy-d-erythro-hexo-2,3-diulose in the presence of lysine leads to formation of carboxylic acid amides
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A novel species of amides formed from degradation of one of the most important key intermediates in Maillard hexose chemistry-1-deoxyhexo-2,3- diulose-was investigated. In 1-deoxyhexo-2,3-diulose/Nα-t-BOC- lysine reaction mixtures four amides, Nε-acetyl lysine, N ε-formyl lysine, Nε-lactoyl lysine and N ε-glycerinyl lysine, were identified and their structures verified by authentic reference standards. Amides and corresponding carboxylic acids (acetic acid, formic acid, lactic acid and glyceric acid) accumulated over time. Both Nε-lysine amides and carboxylic acids were thus determined as stable Maillard end products. Results of model incubations suggested the synthesis of amides to be mechanistically closely related to the formation of their corresponding carboxylic acids by β-dicarbonyl cleavage. Due to the different chemical properties of all the compounds monitored, various analytical strategies had to be carried out (LC-MS2, GC-MS, GC-FID, enzymatic determination).
- Smuda, Mareen,Voigt, Michael,Glomb, Marcus A.
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experimental part
p. 6458 - 6464
(2011/08/09)
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- Decomposition of copper-amino acid complexes by sodium sulfide
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Sodium sulfide very efficiently removes copper from protected amino acid-copper complexes. The copper in the amino acid complex was reduced to insoluble cuprous sulfide and the free amino acid was released in pure form. This method is very convenient and rapid, requiring only 5-10 min and 0.55-0.75 equiv of sodium sulfide.
- Nowshuddin, Shaik,Reddy, A. Ram
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p. 5159 - 5161
(2007/10/03)
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Molecular rotations of N(α)-acyl-L-lysines at various pH values
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Molecular rotations of N(α)-acyl-L-lysines were determined in water and in water containing various amounts of HCl or NaOH. The acyl groups were formyl, acetyl, propionyl, and butyryl. Each N(α)-acyl-L-lysine exhibited more negative rotation in HCl or NaOH solution than in water. The plot of molecular rotation against amount of HCl or NaOH resembled that of a D-α-amino acid even though N(α)-acyl-lysine was of L-form. The reason for this is discussed from the standpoint of steric factors. N(ε)-Acyl-L-lysines corresponding to the N(α)-acyl-L-lysines were synthesized as reference compounds. It was found that water-soluble N(ε)-acyl-L-lysines can be easily prepared by acylation of the Cu complex solution of L-lysine hydrochloride in the presence of triethylamine. The molecular rotation plots for N(ε)-acyl-L-lysines were typical of L-α-amino acids.
- Soejima,Akagi,Izumiya
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p. 2618 - 2620
(2007/10/02)
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- Cosmetic composition containing DOPA derivatives
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A composition for topical application to human hair or skin contains a chemical analogue of dihydroxyphenyl alanine (DOPA). This chemical analogue can be absorbed by skin or by a hair follicle and metabolised in-vivo, thus leading to the formation of melanin in skin or to the growth of melanin-pigmented hair. Consequently the composition can give controlled skin darkening to mimic sun-induced tanning or can bring about the growth of dar hair in place of the grey or white hair.
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- Cosmestic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamic acid derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Hair growth composition containing citric acid esters
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Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
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- N-METHOXYDIACETAMIDE: A NEW SELECTIVE ACETYLATING AGENT
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A simple and efficient method for the direct chemoselective acetylation of primary amines in the presence of alcohols or secondary amines using a new reagent N-methoxydiacetamide is described.
- Kikugawa, Yasuo,Mitsui, Kimiyo,Sakamoto, Takeshi,Kawase, Masami,Tamiya, Hiroshi
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p. 243 - 246
(2007/10/02)
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