Tryptophan is abundantly found on the surface of bacteriocins, venoms and other membrane-active proteins of medical relevance. While many are highly conserved, it is often difficult to elucidate their function based only on site-directed mutagenesis. Indeed, the heterocyclic ring of tryptophan exhibits a wide spectrum of polarity that has been demonstrated to interact with various components of the lipid membrane domains. It can associate with a cationic group such as choline through π-based interactions, the hydrophobic alkyl chain of a fatty acid or amino acid, or a H-bond acceptor such as the phosphate head group by donating the indole’s N-H. In line with the dynamical nature of proteins, a tryptophan residue may have multiple interacting partners that interchange during the course of action. Indeed, while each tryptophan residue found on the surface of a protein likely plays a defined role in the structure-activity relationship, their diverse modes of interactions complicate mechanistic elucidation. Here you can see how two tryptophan residues are involved in a protein-ligand interactions, as demonstrated by the Crystal structure of catalytic domain of LytB protein from Streptococcus pneumoniae in complex with NAG-NAM-NAG-NAM-NAG peptidolycan analogue (PDB code: 7PJ6)
#molecularart ... #tryptophan ... #ligand ... #interaction ... #hydrophobic ... #residue ... #xray
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #tryptophan ... #ligand ... #interaction ... #hydrophobic ... #residue ... #xray
Structure rendered with @proteinimaging and depicted with @corelphotopaint
