The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

摘要: We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides peptide synthesis. TOAC was first spin label probe incorporated by means a bond. In view rigid character this cyclic molecule attachment to backbone via bond, incorporation has been very useful analyze dynamics secondary structure. Many these were performed making use EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, FT-IR, have employed. The double-labeled synthetic allowed investigation their A large number focused interaction peptides, both biologically active, with membranes. latter case, reported ligands fragments GPCR, host defense phospholamban, β-amyloid. macroscopically aligned samples provided information orientation More recent peptide–protein peptide–nucleic interactions. Moreover, shown be valuable for relaxation enhancement NMR labeled proteins. growth TOAC-related publications suggests that unnatural will find increasing future.