Random coil shifts of posttranslationally modified amino acids.

Most eukaryotic proteins are modified during and/or after translation, regulating their structure, function and localisation. The role of posttranslational modifications (PTMs) in both normal cellular processes and in diseases is already well recognised and methods for detection of PTMs and generation of specifically modified proteins have developed rapidly over the last decade. However, structural consequences of PTMs and their specific effects on protein dynamics and function are not well understood. Furthermore, while random coil NMR chemical shifts of the 20 standard amino acids are available and widely used for residue assignment, dihedral angle predictions and identification of structural elements or propensity, they are not available for most posttranslationally modified amino acids. Here, we synthesised a set of random coil peptides containing common naturally occurring PTMs and determined their random coil NMR chemical shifts under standardised conditions. We highlight unique NMR signatures of posttranslationally modified residues and their effects on neighbouring residues. This comprehensive dataset complements established random coil shift datasets of the 20 standard amino acids and will facilitate identification and assignment of posttranslationally modified residues. The random coil shifts will also aid in determination of secondary structure elements and prediction of structural parameters of proteins and peptides containing PTMs.