CYANA Commands: distances split

Parameters

selection=string

(default: none)

keep=real

(default: 0.25)

exponent=real

(default: 6.0)

extension=real

(default: 1.0)

Description

This command can replace ambiguous distance restraints that match the given selection by several unambiguous distance restraints. By default, the selection made in the most recent distances select command is used, or all distance restraints if no selection has been made so far. Each of the new distance restraints will be assigned uniquely to one of the multiple assignments of the ambiguous input restraint.

The upper distance bound u of a new restraint is obtained from the upper bound u of the corresponding ambiguous input restraint according to the formula

 u = u * (1 + f * ((V/V)^(-1/n) - 1)),

where f and n denote the values of the extension and exponent parameters, respectively, and V/V is the fraction of the total NOESY cross peak volume of the original ambiguous restraint that originates from the single assignment of the new restraint. This volume contribution is computed for each selected structure by assuming an r^-6 distance-to-volume relationship. The average over all conformers of these volume contributions is used for the fraction V/V. Only those assignments for which V/V exceeds the threshold given by the keep parameter are kept to generate an unambiguous distance restraint, others are discarded.