Bridging the gap: A set of selective H-1-N-15-correlations to link sequential neighbors of prolines

Triple-resonance experiments are standard in the assignment of protein spec tra. Conventional assignment strategies use H-1-N-15-correlations as a star ting point and therefore have problems when proline appears in the amino ac id sequence, which lacks a signal in these correlations. Here we present a set of amino acid selective pulse sequences which provide the information t o link the amino acid on either side of proline residues and thus complete the sequential assignment. The experiments yield amino acid type selective H-1-N-15-correlations which contain signals from the amino protons of the r esidues either preceding or following proline in the amino acid sequence. T hese protons are correlated with their own nitrogen or with that of the pro line. The new experiments are recorded as two-dimensional experiments and t heir performance is demonstrated by application to a 115-residue protein do main.