"BEST" homonuclear adiabatic decoupling for C-13- and N-15-double-labeled proteins

The cyclic irradiation sidebands appearing in homonuclear adiabatic decoupl ing are calculated in detail, which reveals the origin of the antisymmetric sidebands. The sidebands can be inverted by inserting an initial decouplin g with a different period, but the same f(1rms) as the main decoupling that is required for Bloch-Siegert shift compensation. The sidebands can be eli minated in a broad decoupling range by adding spectra of opposite sidebands . Based on this scheme, an offset-independent double-adiabatic decoupling, named Bloch-Siegert Shift Eliminated and Cyclic Sideband Trimmed Double-Adi abatic Decoupling, or "BEST" decoupling for short, is constructed, which no t only compensates the Bloch-Siegert shift as shown earlier by Zhang and Go renstein (1998) but also eliminates residual sidebands effectively. (C) 199 9 Academic Press.