FUTURE DIRECTIONS Where Is NMR Taking Us ? *

The last few years have seen a quantum jump both in the size and accuracy of protein structures that can be solved by NMR.l These newest advances in the field are following right on the heels of the earlier development of NMR techniques for threedimensional structure de t e rmina t i~n~ .~ resulting in a substantial number of solution structures of small proteins over of the last decade. Currently it is possible to determine the structures of proteins up to the 15-25 kDa range at a resolution comparable to 2 A resolution crystal structure^.^ This perspective aims at highlighting where current and future developments are taking place, both in the technological arena and in regard to applications to the biological sciences.