Identification of spin diffusion pathways in isotopically labeled biomolecules

One-dimensional NOE experiments applicable to labeled macromolecules are pr esented which allow the manipulation of specific spin diffusion pathways an d thus unambiguously identify clandestine spins through which the direct NO E is mediated. A treatment of spin diffusion using average Liouvillian theo ry is shown to describe adequately these phenomena. Experiments are carried out on an N-15-labeled sample of human ubiquitin, (C) 1999 Academic Press.