Synthesis of chiral nine and twelve-membered cyclic polyamines from natural building blocks.

A rational strategy for the facile and efficient cyclization of amino acid-based linear precursors forming nine and twelve-membered cyclic peptidomimetics is reported. The resulting chiral lactams can readily be reduced to substituted cyclic polyamine analogues of 1,4,7,10-tetraaza-cyclododecane (cyclen) and 1,4,7-triaza-cyclononane (TACN).

New Lanthanide Chelating Tags for PCS NMR Spectroscopy with Reduction Stable, Rigid Linkers for Fast and Irreversible Conjugation to Proteins.

Lanthanide chelating tags (LCTs) have been used with great success for determining structures and interactions of proteins and other biological macromolecules. Recently LCTs have also been used for in-cell NMR spectroscopy, but the bottleneck especially for demanding applications like pseudocontact shift (PCS) NMR is the sparse availability of suitable tags that allow for site-selective, rigid, irreversible, fast, and quantitative conjugation of chelated paramagnetic lanthanide ions to proteins via reduction stable bonds. We report here several such tags and focus on a new pyridine thiazole derivate of DOTA, that combines high affinity, rigidity, and selectivity with unprecedented tagging properties.