NMR offers the possibility of accurate secondary
structure for proteins that would be too large for structure
determination. In the absence of an X-ray crystal structure,
this information should be useful as an adjunct to protein
fold recognition methods based on low resolution force
fields. The value of this information has been tested by
adding varying amounts of artificial secondary structure
data and threading a sequence through a library of candidate
folds. Using a literature test set, the threading method
alone has only a one-third chance of producing a correct
answer among the top ten guesses. With realistic secondary
structure information, one can expect a 60–80% chance
of finding a homologous structure. The method has then
been applied to examples with published estimates of secondary
structure. This implementation is completely independent
of sequence homology, and sequences are optimally aligned
to candidate structures with gaps and insertions allowed.
Unlike work using predicted secondary structure, we test
the effect of differing amounts of relatively reliable
data.