MUSIC, selective pulses, and tuned delays: Amino acid type-selective H-1-N-15 correlations, II

Amino acid type-selective experiments help to remove ambiguities in either manual or automated assignment procedures. Here we present modified triple- resonance experiments that yield amino acid type-selective H-1-N-15 correla tions. They are based on the MUSIC coherence transfer scheme which replaces the initial INEPT transfer and is selective for XH2 or XH3 (where X is eit her N-15 or C-13). Signals of the desired amino acid types are thus selecte d based on the topology of the side chain. MUSIC is combined with selective pulses and carefully tuned delays to create experiments for Ser (S-HSQC); Val, Ile, and Ala (VIA-HSQC); Leu and Ala (LA-HSQC); Asp, Asn, and Gly (DNG -HSQC), as well as Glu, Gln, and Gly (EQG-HSQC). The new experiments are re corded as two-dimensional spectra and their performance is demonstrated by their application to two protein domains of 83 and 115 residues. (C) 2001 A cademic Press.