MECHANISM OF AUTOXIDATIVE GLYCOSYLATION - IDENTIFICATION OF GLYOXAL AND ARABINOSE AS INTERMEDIATES IN THE AUTOXIDATIVE MODIFICATION OF PROTEINS BY GLUCOSE
MECHANISM OF AUTOXIDATIVE GLYCOSYLATION - IDENTIFICATION OF GLYOXAL AND ARABINOSE AS INTERMEDIATES IN THE AUTOXIDATIVE MODIFICATION OF PROTEINS BY GLUCOSE
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DOI：
10.1021/bi00011a027
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发表时间：
1995-03-21
期刊：
影响因子：
2.9
通讯作者：
BAYNES, JW
中科院分区：
文献类型：
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作者：
WELLSKNECHT, KJ;ZYZAK, DV;BAYNES, JW
糖化和氧化反应有助于衰老和糖尿病中的蛋白质修饰。葡萄糖自氧化过程中二羰基糖的形成是假设的自氧化糖基化和随后的葡萄糖使蛋白质褐变的第一步[Wolff, S. P., and Dean, R. T. (1987) Biochem. J. 245, 243-250]。为了鉴定生理条件下葡萄糖自动氧化过程中形成的二羰基糖，将葡萄糖在空气（氧化条件）或氮气和过渡金属螯合剂（抗氧化条件）下于37℃在磷酸盐缓冲液（pH 7.4）中孵育。与 Girard-T 试剂反应后，对二羰基化合物进行分光光度法和 HPLC 分析。通过气相色谱-质谱法分析碳水化合物。在氧化条件下进行的孵育中，二羰基糖和阿拉伯糖的浓度随着时间和葡萄糖浓度的增加而增加；在抗氧化条件下孵育的葡萄糖中仅检测到痕量的这些产物。用 Girard-T 试剂形成的加合物的 HPLC 分析表明乙二醛是葡萄糖自动氧化形成的唯一 α-二羰基糖。在 21 天的培养过程中，乙二醛和阿拉伯糖占葡萄糖损失的 50% 以上。葡萄糖酮及其降解产物核酮糖均未检测到。乙二醛与 RNase 反应产生糖氧化产物 N ε-(羧甲基)赖氨酸，而阿拉伯糖是戊糖苷的来源。我们的结果表明乙二醛和阿拉伯糖是氧化条件下葡萄糖使蛋白质褐变和交联的中间体。它们还提供了一种机制，通过该机制，抗氧化剂和二羰基捕获剂（例如氨基胍）限制糖氧化反应，并支持进一步评估这些类型的化合物在衰老和糖尿病过程中抑制蛋白质化学修饰和交联的作用。
Glycation and oxidation reactions contribute to protein modification in aging and diabetes. Formation of dicarbonyl sugars during autoxidation of glucose is the hypothetical first step in the autoxidative glycosylation and subsequent browning of proteins by glucose [Wolff, S. P., and Dean, R. T. (1987) Biochem. J. 245, 243-250]. In order to identify the dicarbonyl sugar(s) formed during autoxidation of glucose under physiological conditions, glucose was incubated in phosphate buffer (pH 7.4) at 37 degrees C under air (oxidative conditions) or nitrogen with transition metal chelators (antioxidative conditions). Dicarbonyl compounds were analyzed spectrophotometrically and by HPLC after reaction with Girard-T reagent. Carbohydrates were analyzed by gas chromatography-mass spectrometry. Both dicarbonyl sugar and arabinose concentrations increased with time and glucose concentration in incubations conducted under oxidative conditions; only trace amounts of these products were detected in glucose incubated under antioxidative conditions. HPLC analysis of adducts formed with Girard-T reagent indicated that glyoxal was the only a-dicarbonyl sugar formed on autoxidation of glucose. Glyoxal and arabinose accounted for greater than or equal to 50% of the glucose lost during a 21 day incubation. Neither glucosone nor its degradation product, ribulose, was detectable. Reaction of glyoxal with RNase yielded the glycoxidation product, N epsilon-(carboxymethyl)lysine, while arabinose is a source of pentosidine. Our results implicate glyoxal and arabinose as intermediates in the browning and crosslinking of proteins by glucose under oxidative conditions. They also provide a mechanism by which antioxidants and dicarbonyl trapping reagents, such as aminoguanidine, limit glycoxidation reactions and support further evaluation of these types of compounds for inhibition of chemical modification and crosslinking of proteins during aging and diabetes.