DETECTION AND IDENTIFICATION OF A PROTEIN-BOUND IMIDAZOLONE RESULTING FROM THE REACTION OF ARGININE RESIDUES AND METHYLGLYOXAL
DETECTION AND IDENTIFICATION OF A PROTEIN-BOUND IMIDAZOLONE RESULTING FROM THE REACTION OF ARGININE RESIDUES AND METHYLGLYOXAL
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DOI：
10.1007/bf01192954
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发表时间：
1994-07-01
期刊：
影响因子：
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通讯作者：
KLOSTERMEYER, H
中科院分区：
文献类型：
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作者：
HENLE, T;WALTER, AW;KLOSTERMEYER, H
茚三酮阳性化合物中检测到酸水解的各种碱处理的烘焙产品（椒盐卷饼，小吃店），洗脱后立即吡啶氨基酸色谱图。在从食物样品中制备性分离和独立合成后，通过快原子轰击质谱、H-1-和C-13-核磁共振明确鉴定该化合物为蛋白质结合的咪唑酮，以两种互变异构形式存在，即N（δ）-（5-甲基-4-氧代-5-氢咪唑-2-基）-L-鸟氨酸和N（δ）-（4-甲基-5-氧代-4-氢咪唑-2-基）-L-鸟氨酸。酸不稳定的氨基酸衍生物是由精氨酸的胍基和甲基乙二醛（一种糖降解产物）直接缩合形成的，代表了一种以前未知的翻译后蛋白质修饰。对于许多市售的碱处理的烘焙产品，在完全酶消化后，咪唑酮的量在900和1300 mg/100 g蛋白质之间，表明在烘焙过程中，20和30%之间的乙酰基残基可能与甲基乙二醛反应。
A ninhydrin-positive compound was detected in acid hydrolysates of various alkali-treated bakery products (pretzels, snack bars), eluting immediately after pyridosine in amino acid chromatograms. Following preparative isolation from a food sample and independent synthesis, the compound was unequivocally identified by fast-atom bombardement-mass spectrometry, H-1- and C-13-nuclear magnetic resonance as a protein-bound imidazolone, existing in two tautomeric forms, namely N(delta)-(5-methyl-4-oxo-5-hydroimidazol-2-yl)-L-ornithine and N(delta)-(4-methyl-5-oxo-4-hydroimidazol-2-yl)-L-ornithine. The acid-labile amino acid derivative is formed by direct condensation of the guanido group of arginine and methylglyoxal, a sugar degradation product, and represents a previously unknown post-translational protein modification. For a number of commercially available alkali-treated bakery products, the amounts of the imidazolone after complete enzymic digestion ranged between 900 and 1300 mg per 100 g protein, indicating that between 20 and 30% of the arginyl residues might react with methylglyoxal during the bakery process.