Instituto de la Grasa, Consejo Superior de Investigaciones Científicas, Avenida Padre García Tejero 4, 41012-Seville, Spain.
Food Chem. 2013 Nov 15;141(2):1140-6. doi: 10.1016/j.foodchem.2013.03.068. Epub 2013 Mar 26.
The ability of α-keto acids to covert amino acids into Strecker aldehydes was investigated in an attempt to both identify new pathways for Strecker degradation, and analyse the role of α-keto acids as intermediate compounds in the formation of Strecker aldehydes by oxidised lipids. The results obtained indicated that phenylalanine was converted into phenylacetaldehyde to a significant extent by all α-keto acids assayed; glyoxylic acid being the most reactive α-keto acid for this reaction. It has been proposed that the reaction occurs by formation of an imine between the keto group of the α-keto acid, and the amino group of the amino acid. This then undergoes an electronic rearrangement with the loss of carbon dioxide to produce a new imine. This final imine is the origin of both the Strecker aldehyde and the amino acid from which the α-keto acid is derived. When glycine was incubated in the presence of 4,5-epoxy-2-decenal, the amino acid was converted into glyoxylic acid, and this α-keto acid was then able to convert phenylalanine into phenylacetaldehyde. All these results suggest that Strecker aldehydes can be produced by amino acid degradation initiated by different reactive carbonyl compounds, included those coming from amino acids and proteins. In addition, α-keto acids may act as intermediates for the Strecker degradation of amino acids by oxidised lipids.
研究了α-酮酸将氨基酸转化为斯特雷克醛的能力，试图确定斯特雷克降解的新途径，并分析α-酮酸作为氧化脂质形成斯特雷克醛过程中中间化合物的作用。结果表明，所有测定的α-酮酸都能将苯丙氨酸转化为苯乙醛；乙醛酸是该反应最具反应性的α-酮酸。据推测，该反应是通过α-酮酸的酮基与氨基酸的氨基之间形成亚胺来发生的。然后，它会发生电子重排，失去二氧化碳，产生新的亚胺。最后这个亚胺既是斯特雷克醛，也是氨基酸的来源，而α-酮酸则来源于该氨基酸。当甘氨酸在 4,5-环氧-2-癸烯醛存在下孵育时，氨基酸转化为乙醛酸，然后这种α-酮酸可以将苯丙氨酸转化为苯乙醛。所有这些结果表明，斯特雷克醛可以通过不同的反应性羰基化合物（包括来自氨基酸和蛋白质的化合物）引发的氨基酸降解来产生。此外，α-酮酸可能作为氧化脂质对氨基酸的斯特雷克降解的中间产物发挥作用。
