Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, United States of America.
Applications Lab, TA Instruments, Lindon, Utah, United States of America.
PLoS One. 2023 Mar 17;18(3):e0271008. doi: 10.1371/journal.pone.0271008. eCollection 2023.
Differential scanning calorimetry (DSC) can indicate changes in structure and/or concentration of the most abundant proteins in a biological sample via heat denaturation curves (HDCs). In blood serum for example, HDC changes result from either concentration changes or altered thermal stabilities for 7-10 proteins and has previously been shown capable of differentiating between sick and healthy human subjects. Here, we compare HDCs and proteomic profiles of 50 patients experiencing joint-inflammatory symptoms, 27 of which were clinically diagnosed with rheumatoid arthritis (RA). The HDC of all 50 subjects appeared significantly different from expected healthy curves, but comparison of additional differences between the RA and the non-RA subjects allowed more specific understanding of RA samples. We used mass spectrometry (MS) to investigate the reasons behind the additional HDC changes observed in RA patients. The HDC differences do not appear to be directly related to differences in the concentrations of abundant serum proteins. Rather, the differences can be attributed to modified thermal stability of some fraction of the human serum albumin (HSA) proteins in the sample. By quantifying differences in the frequency of artificially induced post translational modifications (PTMs), we found that HSA in RA subjects had a much lower surface accessibility, indicating potential ligand or protein binding partners in certain regions that could explain the shift in HSA melting temperature in the RA HDCs. Several low abundance proteins were found to have significant changes in concentration in RA subjects and could be involved in or related to binding of HSA. Certain amino acid sites clusters were found to be less accessible in RA subjects, suggesting changes in HSA structure that may be related to changes in protein-protein interactions. These results all support a change in behavior of HSA which may give insight into mechanisms of RA pathology.
差示扫描量热法 (DSC) 可以通过热变性曲线 (HDC) 指示生物样品中最丰富蛋白质的结构和/或浓度变化。例如，在血清中，HDC 的变化源于蛋白质浓度的变化或热稳定性的改变，对于 7-10 种蛋白质，以前已经证明其能够区分健康和患病的人类受试者。在这里，我们比较了 50 名患有关节炎症症状的患者的 HDC 和蛋白质组谱，其中 27 名被临床诊断为类风湿关节炎 (RA)。所有 50 名患者的 HDC 明显与预期的健康曲线不同，但比较 RA 和非 RA 患者之间的其他差异可以更具体地了解 RA 样本。我们使用质谱 (MS) 来研究在 RA 患者中观察到的额外 HDC 变化背后的原因。HDC 差异似乎与丰富的血清蛋白浓度差异没有直接关系。相反，这些差异可以归因于样品中部分人血清白蛋白 (HSA) 蛋白的热稳定性改变。通过定量分析人工诱导的翻译后修饰 (PTM) 频率的差异，我们发现 RA 患者的 HSA 表面可及性明显降低，这表明在某些区域存在潜在的配体或蛋白质结合伴侣，这可以解释 RA HDC 中 HSA 熔融温度的偏移。发现 RA 患者中一些低丰度蛋白质的浓度有显著变化，可能与 HSA 的结合有关。某些氨基酸位点簇在 RA 患者中不易接近，这表明 HSA 结构发生变化，这可能与蛋白质-蛋白质相互作用的变化有关。这些结果均支持 HSA 行为的改变，这可能有助于深入了解 RA 病理机制。
