SPIN-STATE-SELECTIVE COHERENCE TRANSFER VIA INTERMEDIATE STATES OF 2-SPIN COHERENCE IN IS SPIN SYSTEMS - APPLICATION TO E.COSY-TYPE MEASUREMENT OF J-COUPLING-CONSTANTS

It is demonstrated that a new pulse sequence element, Spin-State-Selec tive Coherence Transfer ((SCT)-C-3), via an intermediate slate of hete ronuclear IS zero-or double-quantum coherence can transfer the two sin gle-quantum coherences on one of the spins exclusively to any one of t he two single-quantum coherences on the other spin. This fact is used for editing into two subspectra that are most suitable for extraction of home-or heteronuclear J coupling constants when (SCT)-C-3 is combin ed with homonuclear coherence transfer-during a mixing period. Experim ental confirmation is obtained using a N-15-labeled 58-residue protein , the C-terminal Kunitz domain from human type VI collagen. The J coup ling constants determined include (3)J(HN-H alpha) and (3)J(N-H beta) related to the phi and chi(1) angles, respectively.