New Applications for Residual Dipolar Couplings: Extending the Range of NMR in Structural Biology

Abstract

Less than 10 years since their introduction, residual dipolar couplings (RDCs) have become a mainstay in Nuclear Magnetic Resonance (NMR) methodology [1--4]. Dipolar couplings are anisotropic through-space interactions between magnetic nuclei. In solution samples, Brownian motion causes all orientations to be sampled with the same probability; there is no net anisotropic orientation needed in order for the dipolar coupling to be observed. However, there have been recent advances where the presence of various types of solution media imparts a small degree of anisotropy, a RDC [5,6]. Under these conditions, the molecule retains isotropic properties such as rapid tumbling and narrow line widths.