692-04-6Relevant articles and documents
Acetyl radical production by the methylglyoxal-peroxynitrite system: A possible route for l-lysine acetylation
Massari, Julio,Tokikawa, Rita,Zanolli, Luiz,Tavares, Marina Franco Maggi,Assuncao, Nilson Antonio,Bechara, Etelvino Jose Henriques
, p. 1762 - 1770 (2010)
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.
Peptide Tyrosinase Activators
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, (2015/06/10)
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.
Degradation of 1-deoxy-d-erythro-hexo-2,3-diulose in the presence of lysine leads to formation of carboxylic acid amides
Smuda, Mareen,Voigt, Michael,Glomb, Marcus A.
experimental part, p. 6458 - 6464 (2011/08/09)
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).
