A maximum entropy derivation of the integrated direct methods–isomorphous replacement or integrated direct methods–anomalous scattering probability distributions

Bryan, R. K.

doi:10.1107/s010876738800371x

Cited by 2 publications

(1 citation statement)

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“…Bryan (1988) has discussed the derivation of probability distributions for isomorphous replacement and anomalous dispersion by use of a maximum-entropy formalism. Use was made of two density maps, one representing a native structure and the other representing heavy atoms or anomalous scatterers.…”

Section: Pj(oj)=(1/kj)exp[ajcos(g2j-%)]mentioning

confidence: 99%

Direct methods in protein crystallography

Karle¹

1989

Acta Cryst Sect A

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It is pointed out that the 'direct methods' of phase determination for small-structure crystallography do not have immediate applicability to macromolecular structures. The term 'direct methods in macromolecular crystallography' is suggested to categorize a spectrum of approaches to macromolecular structure determination in which the analyses are characterized by the use of two-phase and higher-order-phase invariants. The evaluation of the invariants is generally obtained by the use of heavy-atom techniques. The results of a number of the more recent algebraic and probabilistic studies involving isomorphous replacement and anomalous dispersion thus become valid subjects for discussion here. These studies are described and suggestions are also presented concerning future applicability. Additional discussion concerns the special techniques of filtering, the use of non-crystallographic symmetry, some features of maximum entropy and attempts to apply phase-determining formulas to the refinement of macromolecular structure. It is noted that, in addition to the continuing remarkable progress in macromolecular crystallography based on the traditional applications of isomorphous replacement and anomalous dispersion, recent valuable advances have been made in the application of non-crystallographic symmetry, in particular, to virus structures and in applications of filtering. Good progress has also been reported in the application of exact linear algebra to multiple-wavelength anomalous-dispersion investigations of structures containing anomalous scatterers of only moderate scattering power.

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Section: Pj(oj)=(1/kj)exp[ajcos(g2j-%)]mentioning

confidence: 99%