A Double‐Armed, Hydrophilic Transition Metal Complex as a Paramagnetic NMR Probe

Abstract

Synthetic metal complexes can be used as paramagnetic probes for the study of proteins and protein complexes.H erein, two transition metal NMR probes (TraNPs) are reported. TraNPs are attached through two arms to ap rotein to generate ap seudocontact shift (PCS) using cobalt(II), or paramagnetic relaxation enhancement (PRE) with manganese(II). The PCS analysis of TraNPs attached to three different proteins shows that the size of the anisotropic component of the magnetic susceptibility depends on the probe surroundings at the surface of the protein, contrary to what is observed for lanthanoid-based probes.T he observed PCS are relatively small, making cobalt-based probes suitable for localized studies,such as of an active site.The obtained PREs are stronger than those obtained with nitroxide spin labels and the possibility to generate both PCS and PRE offers advantages.T he properties of TraNPs in comparison with other cobalt-based probes are discussed. No. 510, ZhongzhengRd.,X inzhuang Dist.,N ew Taipei City 24205 (Taiwan) Supportinginformation, includings ynthesis and analysis procedures, and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.