Department of Biophysics, Molecular Biology & Bioinformatics, University of Calcutta, 92, Acharyya Prafulla Chandra Road, Kolkata 700009, India.
Int J Biol Macromol. 2021 Dec 15;193(Pt B):2165-2172. doi: 10.1016/j.ijbiomac.2021.11.047. Epub 2021 Nov 11.
Methylglyoxal (MG) is a highly reactive α-dicarbonyl compound which reacts with proteins to form advanced glycation end products (AGEs). MG-induced AGE (MAGE) formation is particularly significant in diabetic condition. In the current study, we have undertaken a time-dependant characterization of MG-modified myoglobin following incubation of the heme protein with the α-dicarbonyl compound for different time periods. Interestingly, mass spectrometric studies indicated modifications at two specific lysine residues, Lys-87 and Lys-133. The AGE adducts identified at Lys-87 were carboxymethyllysine and carboxyethyllysine, while those detected at Lys-133 included pyrraline-carboxymethyllysine and carboxyethyllysine, respectively. Far-UV CD studies revealed a decrease in the native α-helical content of the heme protein gradually with increasing time of MG incubation. In addition, MG modification was found to induce changes in tertiary structure as well as surface hydrophobicity of the heme protein. MG-derived AGE adducts thus appear to alter the structure of Mb considerably. Considering the increased level of MG in diabetic condition, the current study appears physiologically relevant in terms of understanding AGE-mediated protein modification and subsequent structural changes.
甲基乙二醛（MG）是一种高度反应性的α-二羰基化合物，可与蛋白质反应形成晚期糖基化终末产物（AGEs）。MG 诱导的 AGE（MAGE）形成在糖尿病情况下尤为显著。在本研究中，我们对血红素蛋白与α-二羰基化合物孵育不同时间后的 MG 修饰肌红蛋白进行了时间依赖性特征分析。有趣的是，质谱研究表明在两个特定的赖氨酸残基 Lys-87 和 Lys-133 上发生了修饰。在 Lys-87 上鉴定出的 AGE 加合物为羧甲基赖氨酸和羧乙基赖氨酸，而在 Lys-133 上检测到的加合物分别为吡咯啉-羧甲基赖氨酸和羧乙基赖氨酸。远紫外 CD 研究表明，随着 MG 孵育时间的增加，血红素蛋白的天然α-螺旋含量逐渐减少。此外，MG 修饰被发现诱导血红素蛋白的三级结构和表面疏水性发生变化。因此，MG 衍生的 AGE 加合物似乎会使 Mb 的结构发生很大变化。考虑到糖尿病条件下 MG 水平的升高，本研究在理解 AGE 介导的蛋白质修饰和随后的结构变化方面似乎具有生理相关性。
