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 predic ting transfer maxima/minima. For certain topologies, the intrinsically comp lex expressions describing the transfer functions reduce to compact forms w hich are easy to interpret and analyze. For other topologies where compacti fication is not possible, an analysis of the component functions of the T-k l reveals that only one or two components contribute significantly to the o verall profile of the transfer function. As a result, simple rules of the t humb may be devised for reasonably accurate prediction of mixing times corr esponding to local and global transfer maximal minima, thereby facilitating mixing time optimization in TOCSY experiments. (C) 2000 Academic Press.