MANCHESTER, U.K.—Heteronuclear multidimensional NMR has been useful in studies of protein-protein and protein-ligand interactions. For many drug discovery efforts, however, researchers are looking at compounds that interact simultaneously with two proteins—a complex that is difficult to visualize with current isotopic labeling methods. Researchers at the University of Manchester and Bruker Biospin may have found a solution to this technical challenge.
As they report in JACS, they used 15N labeling of the protein partners to identify interactions between unlabeled ligand and each protein, but to distinguish the resonances of one protein from the other, they also labeled one with 13C. Thus, the amide peaks of similar residues could be differentiated by the 12C or 13C atom to which they were attached.
They tested their isotopically discriminated (IDIS) NMR method on a triple-member complex of 15N-labeled WW domain pair, 13C,15N-labeled receptor peptide, and unlabeled proline-rich peptide. The method allowed them to clearly distinguish the interactions between the three partner molecules at sensitivities only slightly lower than when interactions were examined pairwise. From the researchers perspective, the prime advantage of the new method is that it allows scientists to study multipartner interactions under identical experimental conditions.