IMPROVED DILUTE BICELLE SOLUTIONS FOR HIGH-RESOLUTION NMR OF BIOLOGICAL MACROMOLECULES

Dissolving biological macromolecules in dilute bicelle solutions, whic h form oriented liquid crystals in the presence of a magnetic field, p ermits measurement of anisotropic spin interactions such as dipolar co uplings [Tjandra, N. and Bax, A., Science, 278, 1111-1114]. However, t he Lifetimes and temperature ranges of orientation for these samples a re critically dependent on sample composition and experimental conditi ons. This paper demonstrates that doping dilute bicelle solutions with small amounts of charged amphiphiles substantially improves the stabi lity and degree of alignment, as well as extends the temperature range of orientation for these systems. An explanation of the dependence of bicelle aggregation on sample composition is proposed based on the DL VO theory of colloids.