Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
J Am Chem Soc. 2009 Oct 21;131(41):14761-7. doi: 10.1021/ja903233w.
A new lanthanide chelating tag (M8) for paramagnetic labeling of biomolecules is presented, which is based on an eight-fold, stereoselectively methyl-substituted DOTA that can be covalently linked to the host molecule by a single disulfide bond. The steric overcrowding of the DOTA scaffold leads to an extremely rigid, kinetically and chemically inert lanthanide chelator. Its steric bulk restricts the motion of the tag relative to the host molecule. These properties result in very large pseudocontact shifts (>5 ppm) and residual dipolar couplings (>20 Hz) for Dy-M8 linked to ubiquitin, which are unprecedented for a small, single-point-attachment tag. Such large pseudocontact shifts should be well detectable even for larger proteins and distances beyond approximately 50 A. Due to its exceptionally high stability and lanthanide affinity M8 can be used under extreme chemical or physical conditions, such as those applied for protein denaturation, or when it is undesirable that buffer or protein react with excess lanthanide ions.
一种新的镧系螯合物标签（M8）用于生物分子的顺磁标记，它基于一个八倍，立体选择性甲基取代的 DOTA，可以通过单个二硫键与宿主分子共价连接。DOTA 支架的空间拥挤导致了非常刚性的，动力学和化学惰性的镧系螯合剂。其庞大的体积限制了标记相对于宿主分子的运动。这些性质导致与泛素连接的 Dy-M8 产生非常大的赝接触位移（>5 ppm）和残余偶极耦合（>20 Hz），这对于小的单点附着标记来说是前所未有的。即使对于更大的蛋白质和距离超过大约 50 A，如此大的赝接触位移也应该很容易检测到。由于其异常高的稳定性和镧系亲和力，M8 可以在极端的化学或物理条件下使用，例如应用于蛋白质变性的条件，或者当不希望缓冲液或蛋白质与过量的镧系离子反应时。
