A set of BEST triple-resonance experiments for time-optimized protein resonance assignment A series of sequential, intra-residue, and bi-directional BEST H–N–CA, H–N–CO, and H–N–CB pulse sequences is presented that extends the BEST concept introduced recently for fast multidimensional protein NMR [Schanda et al., J. Am. Chem. Soc. 128 (2006) 9042] to the complete set of experiments required for sequential resonance assignment. We demonstrate for the protein ubiquitin that 3D BEST H–N–C correlation spectra can be recorded on a 600 MHz NMR spectrometer equipped with a cryogenic probe in only a few minutes of acquisition time with sufficient sensitivity to detect all expected cross peaks. 187 1 163-169 163-169 Elsevier