Paramagnetic labelling of proteins and oligonucleotides for NMR

Paramagnetic effects offer a rich source of long-range structural restraints. Here we review current methods for site-specific tagging of proteins and oligonucleotides with paramagnetic molecules. The paramagnetic tags include nitroxide radicals and metal chelators. Particular emphasis is placed on tags suitable for site-specific and rigid attachment of lanthanide ions to macromolecules