Albumin is the main nucleophilic target of human plasma: A protective role against pro-atherogenic electrophilic reactive carbonyl species?
Albumin is the main nucleophilic target of human plasma: A protective role against pro-atherogenic electrophilic reactive carbonyl species?
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DOI：
10.1021/tx700349r
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发表时间：
2008-04-01
影响因子：
4.1
通讯作者：
Carini, Marina
中科院分区：
文献类型：
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作者：
Aldini, Giancarlo;Vistoli, Giulio;Carini, Marina
这项工作的目的是研究人血浆中 4-羟基-反式-2-壬烯醛 (HNE) 的代谢命运，它代表反应性羰基物质 (RCS) 形成的主要血管位点，也是主要促动脉粥样硬化靶蛋白形成的地方。当HNE掺入人血浆中时，它迅速消失（40秒内）并且没有检测到I相代谢物，这表明HNE的主要命运是由于内收机制。然后监测两种血浆组分中的 HNE 消耗：低分子量血浆蛋白组分（< 10 kDa；LMWF）和高分子量血浆蛋白组分（> 10 kDa；HMWF）。 HNE 在 LMWF 中几乎稳定，而在 HMV T 中，它在 5 分钟内消耗了近 70%。蛋白质组学将白蛋白 (HSA) 确定为主要蛋白质靶标，脱白蛋白血浆的 HNE 猝灭显着减少进一步证实了这一点。 LC-ESI-MS/MS 分析确定 Cys34 和 Lys199 分别通过形成迈克尔和希夫碱加合物而成为 HSA 反应性最强的加合位点。正如分子模型研究所解释的，白蛋白捕获 HNE 的速率常数为 50.61 +/- 1.89 M-1 s(-1)，Cys34 的速率常数 (29.37 M-1 s(-1)) 比 GSH 的速率常数 (3.81 +/- 0.17 M-1 s(-1)) 高 1 个数量级。总之，我们认为白蛋白通过亲核残基，特别是 Cys34，可以充当循环 RCS 的内源性解毒剂。
The aim of this work was to study the metabolic fate of 4-hydroxy-trans-2-nonenal (HNE) in human plasma, which represents the main vascular site of reactive carbonyl species (RCS) formation and where the main pro-atherogenic target proteins are formed. When HNE was spiked in human plasma, it rapidly disappeared (within 40 s) and no phase I metabolites were detected, suggesting that the main fate of HNE is due to an adduction mechanism. HNE consumption was then monitored in two plasma fractions: low molecular weight plasma protein fractions (< 10 kDa; LMWF) and high molecular weight plasma protein fractions (> 10 kDa; HMWF). HNE was almost stable in LMWF, while in HMV T it was consumed by almost 70% within 5 min. Proteomics identified albumin (HSA) as the main protein target, as further confirmed by a significantly reduced HNE quenching of dealbuminated plasma. LC-ESI-MS/MS analysis identified Cys34 and Lys199 as the most reactive adduction sites of HSA, through the formation of a Michael and Schiff base adducts, respectively. The rate constant of HNE trapping by albumin was 50.61 +/- 1.89 M-1 s(-1) and that of Cys34 (29.37 M-1 s(-1)) was 1 order of magnitude higher with respect to that of GSH (3.81 +/- 0.17 M-1 s(-1)), as explained by molecular modeling studies. In conclusion, we suggest that albumin, through nucleophilic residues, and in particular Cys34, can act as an endogenous detoxifying agent of circulating RCS.