Triple resonance solid state NMR experiments with reduced dimensionality evolution periods

Two solid state NMR triple resonance experiments which utilize the simultan eous incrementation of two chemical shift evolution periods to obtain a spe ctrum with reduced dimensionality are described. The (CO) under bar (N) und er bar CA experiment establishes the correlation of C-13(i-1) to C-13 alpha (i) and N-15(i) by simultaneously encoding the (COi-1)-C-13 and N-15(i) ch emical shifts. The (CA) under bar (N) under bar COCA experiment establishes the correlation Ca-13(i) and (COi)-C-15 to C-13 alpha (i-1) and N-15(i-1) within a single experiment by simultaneous encoding of the Ca-13(i) and N-1 5(i) chemical shifts. This experiment establishes sequential amino acid cor relations in close analogy to the solution state HNCA experiment. Reduced d imensionality 2D experiments are a practical alternative to recording multi ple 3D data sets for the purpose of obtaining sequence-specific resonance a ssignments of peptides and proteins in the solid state. (C) 2001 Academic P ress.