The 20 genetically encoded amino acids provide the basis for most proteins and peptides that make up the machinery of life. This limited repertoire is vastly expanded by the introduction of non-canonical amino acids (ncAAs). Studying the structure of protein-containing ncAAs requires new computational representations that are compatible with existing modelling software. We have developed an online tool for this to aid future structural studies of this class of complex biopolymer.

Having shown that tagging a protein at a single site with different lanthanoid complexes delivers outstanding structural information at a selected site of a protein (such as active sites and ligand binding sites), we now present a simple way by which different lanthanoid complexes can be assembled on a highly solvent-exposed cysteine residue. Furthermore, the chemical assembly is selective for selenocysteine, if a selenocysteine residue can be introduced into the protein of interest.

We show here that binding of the anticancer drug imatinib to the ATP site of Abelson kinase and not binding to its allosteric site coincides with the opening of the kinase regulatory core at nanomolar concentrations. This has implications for the understanding of Abelson’s kinase regulation and activity during medication as well as for the design of new Abelson kinase inhibitors.

Installing a tag containing a paramagnetic metal ion on a protein can lead to large changes (pseudocontact shifts) in the resonances observed in NMR spectra. These are easily measured and contain valuable long-range structural information. The present work shows that a single tagging site furnished with different tags can be sufficient to localise atoms in proteins with high accuracy. In fact, this strategy works almost as well as the same number of tags distributed over multiple tagging sites.

This paper explores a method for determining the solution structure of a solvent-exposed polypeptide segment (the L3 loop), which is next to the active site of the penicillin-degrading enzyme IMP-1. Tagging three different sites on the protein with paramagnetic metal ions allowed positioning of the L3 loop with atomic resolution. It was found that the method was more robust when omitting data obtained with different metal ions if obtained with the same tag at the same tagging site.