Acetylation and glycation of fibrinogen in vitro occur at specific lysine residues in a concentration dependent manner: A mass spectrometric and isotope labeling study

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• 作者：Jan Svensson^a ; ^b ; ^{jan.svensson@ki.se} ; Ann-Charlotte Bergman^a ; Ulf Adamson^b ; Margareta Blombä ; ck^a ; Hå ; kan Wallé ; n^b ; Gun Jö ; rneskog^b
• 关键词：Acetylation ; Glycation ; Mass spectrometry ; Lysine ; Fibrinogen ; Aspirin
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2012
• 期刊代码：159_0006291x
• 类别：bio
• 出版时间：4 May, 2012
• 卷：421
• 期：2
• 页码：335-342
• 文件大小：991 K

摘要

Aspirin may exert part of its antithrombotic effects through platelet-independent mechanisms. Diabetes is a condition in which the beneficial effects of aspirin are less prominent or absent - a phenomenon called 鈥渁spirin resistance鈥? We investigated whether acetylation and glycation occur at specific sites in fibrinogen and if competition between glucose and aspirin in binding to fibrinogen occurs. Our hypothesis was that such competition might be one explanation to 鈥渁spirin resistance鈥?in diabetes. After incubation of fibrinogen in vitro with aspirin (0.8 mM, 24 h) or glucose (100 mM, 5-10 days), we found 12 modified sites with mass spectrometric techniques. Acetylations in the 伪-chain: 伪K191, 伪K208, 伪K224, 伪K429, 伪K457, 伪K539, 伪K562, in the 尾-chain: 尾K233, and in the 纬-chain: 纬K170 and 纬K273. Glycations were found at 尾K133 and 纬K75, alternatively 纬K85. Notably, the lysine 539 is a site involved in FXIII-mediated cross-linking of fibrin. With isotope labeling in vitro, using [¹⁴C-acetyl]salicylic acid and [¹⁴C]glucose, a labeling of 0.013-0.084 and 0.12-0.5 mol of acetylated and glycated adduct/mol fibrinogen, respectively, was found for clinically (12.9-100 渭M aspirin) and physiologically (2-8 mM glucose) relevant plasma concentrations. No competition between acetylation and glycation could be demonstrated. Thus, fibrinogen is acetylated at several lysine residues, some of which are involved in the cross-linking of fibrinogen. This may mechanistically explain why aspirin facilitates fibrin degradation. We find no support for the idea that glycation of fibrin(ogen) interferes with acetylation of fibrinogen.