Convection compensated electrophoretic NMR

A novel method of convection compensated ENMR (CC-ENMR) has been developed to detect electrophoretic motion of ionic species in the presence of bulk s olution convection. This was accomplished using a gradient moment nulling t echnique to remove spectral artifacts from heat-induced convection and usin g the polarity switch of the applied electric field to retain spin phase mo dulations due to electrophoretic flow. Experiments were carried out with a mixture of 100 mM L-aspartic acid and 100 mM 4,9-dioxa-1,12-dodecanediamine to demonstrate this new method of ENMR. CC-ENMR enhances our previously de veloped capillary array ENMR (CA-ENMR) in solving the convection problem. T he combined CA- and CC-ENMR approach strengthens the potential of multidime nsional ENMR in simultaneous structural determination of coexisting protein s and protein conformations in biological buffer solutions of high ionic st rength. Structural mapping of interacting proteins during biochemical react ions becomes possible in the future using ENMR techniques, which may have a profound impact on the understanding of biological events, including prote in folding, genetic control, and signal transduction in general. (C) 2001 A cademic Press.