A stochastic approach to molecular replacement.
The classical approach to the problem of placing n copies of a search model in the asymmetric unit of a target crystal structure is to divide this 6n-dimensional optimization problem into a succession of three-dimensional searches (rotation-function followed by translation-function searches for each of the models). Here, it is shown that a structure-determination method based on a reverse Monte Carlo minimization of a suitably chosen statistic in the 6n-dimensional space defined by the rotational and translational parameters of the n molecules is both feasible and practical, at least for small n. Because all parameters of all molecules are determined simultaneously, this algorithm is expected to improve the signal-to-noise ratio in difficult cases involving high crystallographic/non-crystallographic symmetry in tightly packed crystal forms. Preliminary results from the application of this method (obtained with a space-group general computer program which has been developed for this purpose) are presented.
Glykos
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NM
IMBB, FORTH, 71110 Heraklion, Crete, Greece. glykos@crystal2.imbb.forth.gr
Kokkinidis
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D000818:Animals; D018360:Crystallography, X-Ray / Q000379:methods*; D004527:Egg Proteins / Q000737:chemistry; D009010:Monte Carlo Method; D009113:Muramidase / Q000737:chemistry; D011487:Protein Conformation; D011784:Quail; D012984:Software; D013269:Stochastic Processes; D014422:Turkeys
D004527:Egg Proteins; D009113:Muramidase