OBSERVATION OF INTER-SUBUNIT NUCLEAR OVERHAUSER EFFECTS IN A DIMERIC PROTEIN - APPLICATION TO THE ARC REPRESSOR

For the structure determination of symmetric protein dimers it is necessary to distinguish between intra- and inter-subunit NOEs. A method is presented to measure selectively the inter-subunit NOEs using uniform N-15 and C-13 isotope labelling. This is accomplished by doubly filtered 2D NOE experiments on mixtures of native protein with isotope-labeled protein. The method has been applied to the Arc repressor and allows the characterization of virtually all proton-proton NOEs in terms of their intra- or inter-subunit nature.