Analysis and prediction of isotropic mixing magnetization transfer profiles in three-spin topologies

Isotropic mixing transfer functions (T(kl)) in three-spin systems typical of amino acids have been analyzed in order to develop simple rules for predicting transfer maxima/minima. For certain topologies, the intrinsically complex expressions describing the transfer functions reduce to compact forms which are easy to interpret and analyze. For other topologies where compactification is not possible, an analysis of the component functions of the T(kl) reveals that only one or two components contribute significantly to the overall profile of the transfer function. As a result, simple rules of the thumb may be devised for reasonably accurate prediction of mixing times corresponding to local and global transfer maxima/minima, thereby facilitating mixing time optimization in TOCSY experiments. Copyright 2000 Academic Press.