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11.5 NMR Constraints

Constraints derived from NMR spectroscopy can be incorporated into the CONGEN energy function and used for minimization, simulated annealing using dynamics, or conformational search. The constraints from J-coupling constants can also be used to restrict atom construction in conformational search, see the option, EJCONS, in Miscellaneous Global Options, for more information.

The user may add either a NOE-derived distance constraint term or J-coupling constraint term to the usual potential function when calculating the energy and forces of a macromolecular system. There are two parts to specifying NMR constraints; the NMRC command and the constraints file. The NMRC command signals the program that the NMR constraints are to to be read in and the parameters associated with the function. The specification of which type of constraint function to add is specified in the constraint file. The constraint file is discussed in the following sections.

It also possible to account for conformational flexibility by using ensemble averaging. This facility is still experimental, and you should talk to Bob Bruccoleri or Keith Constantine for more information before using it.

A detailed listing of the NMR constraints can be obtained using the PRINT NMR command, see Print Command.