IDENTIFICATION OF N-2-(1-CARBOXYETHYL)GUANINE (CEG) AS A GUANINE ADVANCED GLYCOSYLATION END-PRODUCT
IDENTIFICATION OF N-2-(1-CARBOXYETHYL)GUANINE (CEG) AS A GUANINE ADVANCED GLYCOSYLATION END-PRODUCT
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DOI：
10.1021/bi00002a032
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发表时间：
1995-01-17
期刊：
影响因子：
2.9
通讯作者：
BUCALA, R
中科院分区：
文献类型：
--
作者：
PAPOULIS, A;ALABED, Y;BUCALA, R
还原糖（如葡萄糖）与蛋白质氨基发生非酶促反应，启动翻译后修饰过程，称为高级糖基化。核苷酸碱基也参与高级糖基化反应，产生DNA连接的高级糖基化终产物（AGEs），导致突变和DNA转座。虽然一些蛋白衍生的AGEs已被分离和结构表征，但AGEs修饰的核苷酸尚未报道。我们系统地研究了模型核苷酸碱基9-甲基鸟嘌呤（9-mG），9-甲基腺嘌呤（9-mA）和1-甲基胞嘧啶（1-mC）对葡萄糖和几种葡萄糖衍生的反应物的反应性。在低温和生理pH下进行的“快速"反应中，1当量核苷酸碱基与10当量D-葡萄糖、D-葡萄糖6-磷酸（G-6-P）、D-葡萄糖6-磷酸/赖氨酸（G-6-P/Lys）、席夫碱1-正丙基氨基-N-D-葡糖苷（SE）或Amadori产物1-正丙基氨基-N-D-果糖（AP）反应。在涉及9-mG的每个反应中，N-2-（1-羧乙基）-9-甲基鸟嘌呤（CEmG）是产生的主要产物。在37 ℃下进行的长期孵育中，9-mG和AP也形成N-2-（1-羧乙基）-9-甲基鸟嘌呤。9-mG与甲基乙二醛（MG），从AP的分解形成的美拉德反应传播的直接处理，也产生了高产率的CEmG。N-2-（1-羧乙基）-9-甲基鸟嘌呤似乎是由鸟嘌呤的伯氨基亲核加成到MG的酮基上，然后分子内重排而产生的。甲基乙二醛是一种已知的原核诱变剂，在真核穿梭载体试验系统中也显示出致突变性。这些数据表明MG是一种葡萄糖衍生的诱变剂，并表明CEmG是DNA高级糖基化的主要产物。
Reducing sugars such as glucose react nonenzymatically with protein amino groups to initiate a posttranslational modification process known as advanced,glycosylation. Nucleotide bases also participate in advanced, glycosylation reactions, producing DNA-linked advanced glycosylation endproducts (AGEs) that cause mutations and DNA transposition. Although several protein-derived AGEs have been isolated and structurally characterized, AGE-modified nucleotides have not yet been reported. We systematically examined the reactivities of the model nucleotide bases 9-methylguanine (9-mG), 9-methyladenine (9-mA), and 1-methylcytosine (1-mC) toward glucose and several glucose-derived reactants. In ''fast'' reactions performed at refluxing temperature and physiological pH, 1 equiv of nucleotide base was reacted with 10 equiv of D-glucose, D-glucose 6-phosphate (G-6-P), D-glucose 6-phosphate/lysine (G-6-P/Lys), the Schiff base 1-n-propylamino-N-D-,glucoside (SE), or the Amadori product 1-n-propylamino-N-D-fructose (AP). In every reaction involving 9-mG, N-2-(1-carboxyethyl)-9-methylguanine (CEmG) was a major product which was produced. N-2-(1-carboxyethyl)-9-methylguanine also formed from 9-mG and AP in longterm incubations performed at 37 degrees C. Direct treatment of 9-mG with methylglyoxal (MG), a Maillard reaction propagator that forms from the decomposition of AP, also produced CEmG in high yield. N-2-(1-carboxyethyl)-9-methylguanine appears to result from the nucleophilic addition of the primary amino group of guanine to the ketone group of MG followed by an intramolecular rearrangement. Methylglyoxal is a known prokaryotic mutagen and was shown additionally to be mutagenic in a eukaryotic shuttle vector assay system. These data implicate MG as a glucose-derived mutagen and suggest that CEmG is a major product that forms as a result of DNA-advanced glycosylation.