Double-quantum dipolar recoupling at high magic-angle spinning rates.

A full investigation of the possible homonuclear double-quantum recoupling sequences, based on the RN family of sequences with N < or = 20, is given. Several new RN sequences, R16(6)(5), R18(8)(5), and R18(10)(5), were applied at high magic-angle spinning rates and compared with theory. The R18(10)(5) technique can be used to recouple dipolar couplings at spinning rates up to 39 kHz, and the application of the sequence in an INADEQUATE experiment is shown for a spinning rate of 30 kHz.

Placement of 19F into the center of GB1: effects on structure and stability.

A structural and thermodynamic characterization of 5F-Trp-substituted immunoglobulin binding domain B1 of streptococcal protein G (GB1) was carried out by nuclear magnetic resonance and circular dichroism spectroscopy. A single fluorine reporter atom was positioned at the center of the three-dimensional structure, uniquely poised to be exploited for studying interior properties of this protein. We demonstrate that the introduction of 5F-Trp does not affect the global and local architecture of GB1 and has no influence on the thermodynamic stability.