Jupin Marc, Michiels Paul J, Girard Frederic C, Wijmenga Sybren S
Biophysical Chemistry, Institute for Materials and Molecules, Radboud University, Nijmegen, The Netherlands.
Magn Reson Med. 2015 Feb;73(2):459-68. doi: 10.1002/mrm.25178. Epub 2014 Mar 17.
Accurate metabolite and protein quantification in blood plasma and other body fluids from one single NMR measurement, allowing for improved quantitative metabolic profiling and better assessment of metabolite-protein interactions.
The total protein concentration is derived from the common chemical-shift changes-caused by protein-induced bulk magnetic susceptibility (BMS)-measured on well-accessible and exchange-free metabolite resonances. These BMS shifts are simply obtained by external referencing with respect to 3-(trimethylsilyl)propionic-2,2,3,3-d4 acid, sodium salt in a coaxial insert.
Based on blood-plasma data from five volunteers, the estimated accuracy of the BMS method is ≤ 5% with respect and comparable to the 3.8% error of the standard colorimetric, Biuret, method. Valine, alanine, glucose, leucine, and lactate display no exchange-induced shift changes. Their well-accessible signals act as reliable probes for pure protein-induced BMS. The slopes and intercepts of their chemical-shift change versus protein concentration were derived from metabolite mixtures with (fatted) human and bovine albumin acting as blood-plasma mimics.
The BMS method, demonstrated on blood plasma, can also be used on other samples containing sufficient protein (> 10 g/L). Also, it allows measurement of the presence and sign of exchange-induced chemical-shift changes.
通过单次核磁共振测量对血浆和其他体液中的代谢物和蛋白质进行准确定量，以改进定量代谢谱分析并更好地评估代谢物 - 蛋白质相互作用。
总蛋白浓度源自通过蛋白质诱导的体磁化率（BMS）引起的常见化学位移变化，该变化在易于获取且无交换的代谢物共振上进行测量。这些BMS位移可通过在同轴插入物中相对于3 - （三甲基甲硅烷基）丙酸 - 2,2,3,3 - d4酸的钠盐进行外部参照简单获得。
基于五名志愿者的血浆数据，BMS方法的估计准确度相对于标准比色法（双缩脲法）的3.8%误差而言≤5%且与之相当。缬氨酸、丙氨酸、葡萄糖、亮氨酸和乳酸未显示出交换诱导的位移变化。它们易于获取的信号可作为纯蛋白质诱导的BMS的可靠探针。其化学位移变化相对于蛋白质浓度的斜率和截距源自以（富含脂肪的）人血清白蛋白和牛血清白蛋白作为血浆模拟物的代谢物混合物。
在血浆上得到验证的BMS方法也可用于其他含有足够蛋白质（>10 g/L）的样品。此外，它还能测量交换诱导的化学位移变化的存在和符号。
