Abstract
Transverse relaxation optimized NMR spectroscopy (TROSY) techniques for (1)H-(15)N backbone amide moieties and for (13)CH(3) methyl groups have permitted the development of Hahn spin echo and Carr-Purcell-Meiboom-Gill (CPMG) experiments for characterizing chemical exchange kinetic phenomena on microsecond-millisecond time scales in proteins with molecular masses >50 kDa. This chapter surveys the theoretical bases for TROSY in spin systems subject to chemical exchange linebroadening, the experimental methods that have been developed to quantitatively characterize chemical exchange in large proteins, and the emerging applications to triose phosphate isomerase, hemoglobin, and malate synthase G, with molecular masses ranging from 54 to 82 kDa.