H(C)CH-COSY AND (H)CCH-COSY EXPERIMENTS FOR C-13-LABELED PROTEINS IN H2O SOLUTION

We present three experiments which serve to identify carbon and proton sidechain resonances in C-13-labeled proteins. The first is an improv ement on the previously published H(C)CH-COSY experiment and comprises the application of gradients for coherence selection and a reduction in the phase cycle. The second experiment is a new (H)CCH-COSY with tw o carbon dimensions. The (H)CCH-COSY presents several advantages over the H(C)CH-COSY experiment in terms of better sensitivity, improved re solution and easier identification of amino acid spins systems, The th ird experiment is a 2D proton-edited (H)C(C)H-COSY that allows suppres sion of methylene resonances. All three HCCH-COSY experiments show goo d sensitivity and excellent solvent suppression. The 2D version can be acquired in as little as 45 minutes and the 3D versions acquired over night, The experiments are demonstrated on a C-13-labeled sample of th e second PDZ domain from human phosphatase PTP1E in H2O solution. (C) 1998 Academic Press.