The NOE statement sets up the database for distance restraints, such as interproton distances. This database is used to evaluate , which can be combined with other energy terms (see Chapter 4). The resulting hybrid energy function can be used for simulated annealing or minimization, using the methods described in Chapters 9 and 10. (Example protocols for NMR structure determination are described in Chapter 20.)
For further reading, see Brünger (1991b), Brünger et al. (1986), Brünger et al. (1987), Brünger and Karplus (1991), Clore and Gronenborn (1989, 1991), Kaptein et al. (1985), Nilges, Clore, and Gronenborn (1988a, 1988b), Nilges, Gronenborn, and Clore (1989), and Nilsson et al. (1986).
It should be noted that the NOE facility in X-PLOR can be used to restrain any type of distance between selected atoms; e.g., it is possible to restrain the characteristic hydrogen-bonding pattern of secondary structural elements by using the NOE statement.