A recent paper in Science highlights once again the potential of NMR to yield insights into complex molecular recognition events in critical biological processes.

In this case the authors used a combination of X-ray crystallography and NMR to probe the structure of the extracellular terminus of the CCR5 co-receptor which, in concert with human CD4 and HIV gp120, is crucial for viral entry. The authors applied challenging saturation transfer effects to study the structure of a small synthetic peptide in a ternary complex with two large proteins. The structure of the CCR5 epitope was successfully elucidated and provides essential insights into conserved interactions for viral recognition – even at the level of a single nitrogen atom! This important work opens a new and therefore invaluable avenue into the design of new molecules as drugs for AIDS.