use of ambiguous restraints?

Kristy Downing kristy at
Thu Jul 13 07:49:30 EST 1995

Having read the manuscript describing the use of ambiguous NMR distance
constraints (Nilges, M. J. Mol. Biol. 245, pp645-660, 1995) and the ambiguous
X-PLOR input protocols, I have some questions.

How exactly are both ambiguous and unambiguous restraints incorporated?  Are
unambiguous restraints also expressed in terms of ppm, or are they identified
explicitly by residue number and atom type?

Is a table of assigned chemical shifts part of the input data? Related to this
question, what is the format of the "filename.ppm" file in the ambiguous

Are any of the other input files (besides the noe and ss_bond ones) significantly
different from those used strictly for calculations with unambiguous restraints?

Finally, I do not understand the application of pseudoatom corrections to
distances associated with unassigned peaks.

Thanks for any helpful advice,

Kristy Downing

Dr A. Kristina Downing			
Oxford University			tel.	01865-275956
Department of Biochemistry		fax.	01865-275253
Oxford  OX1 3QU  ENGLAND		e-mail: kristy at

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