Department of Chemistry and Biochemistry, McCardell Bicentennial Hall, Middlebury College, Middlebury, VT 05753, USA.
Biochem Biophys Res Commun. 2011 Apr 1;407(1):191-6. doi: 10.1016/j.bbrc.2011.02.138. Epub 2011 Mar 2.
Glycation of horse heart metmyoglobin with d-ribose 5-phosphate (R5P), d-2-deoxyribose 5-phosphate (dR5P), and d-ribose with inorganic phosphate at 37°C generates an altered protein (Myo-X) with increased SDS-PAGE mobility. The novel protein product has been observed only for reactions with the protein myoglobin and it is not evident with other common sugars reacted over a 1 week period. Myo-X is first observed at 1-2 days at 37°C along with a second form that is consistent in mass with that of myoglobin attached to several sugars. MALDI mass spectrometry and other techniques show no evidence of the cleavage of a peptide from the myoglobin chain. Apomyoglobin in reaction with R5P also exhibited this protein form suggesting its occurrence was not heme-related. While significant amounts of O(2)(-) and H(2)O(2) are generated during the R5P glycation reaction, they do not appear to play roles in the formation of the new form. The modification is likely due to an internal cross-link formed during a glycation reaction involving the N-terminus and an internal amine group; most likely the neighboring Lys133. The study shows the unique nature of these common pentose sugars in spontaneous glycation reactions with proteins.
在 37°C 下，用 d-核糖 5-磷酸（R5P）、d-2-脱氧核糖 5-磷酸（dR5P）和无机磷酸盐对马心脏肌红蛋白进行糖化，会生成一种具有更高 SDS-PAGE 迁移率的变性蛋白（Myo-X）。这种新的蛋白产物仅在肌红蛋白与这些糖发生反应时观察到，而在其他常见糖发生反应的 1 周内并未观察到。Myo-X 在 37°C 下反应 1-2 天即可首次观察到，同时还存在第二种形式，其质量与与多个糖结合的肌红蛋白一致。MALDI 质谱和其他技术均未显示出从肌红蛋白链上切割肽的证据。R5P 与脱辅基肌红蛋白的反应也表现出这种蛋白形式，表明其形成与血红素无关。尽管在 R5P 糖化反应中会产生大量的 O(2)(-)和 H(2)O(2)，但它们似乎不会在新形式的形成中发挥作用。这种修饰可能是由于涉及 N 末端和内部胺基的糖化反应中形成的内部交联所致；最有可能的是邻近的 Lys133。该研究表明这些常见戊糖在蛋白质的自发糖化反应中具有独特的性质。
