Direct Phasing in Crystallography

TRAMA

Direct methods are now used in a variety of cases: X-ray, neutron or electron data; single crystal and powder data; small molecules and macromolecules. While direct methods solved in practice the phase problem for small molecules, their application to macromolecules is recent and still<BR>undergoing development. This book describes the fundamental methods; in particular it is shown how the methods can be optimized for powder, neutron or electron data, and how they can be integrated with isomorphous replacement, molecular replacement and anomalous dispersion techniques. Maximum<BR>entropy methods are also described and discussed. Sets of test structures are used throughout the various chapters to verify the mathematical techniques and to provide practical examples. This book offers both a comprehensive description of direct methods in crystallography and an invaluable<BR>reference tool. The first three chapters provide an introduction to the field, with sufficient material to constitute a university course. Subsequent chapters are aimed at graduate students and working crystallographers. Basic results are described and discussed in the main body of the text, while<BR>the appendices complement these with in depth mathematical details. The quoted literature is extremely wide and the interested reader can find suggestions for future work and further reading throughout the book.

NOTE EDITORE

Direct methods are, at present, applied to a large variety of cases: X-ray, neutron or electron data; single crystal and powder data; small molecules and macromolecules. While direct methods solved in practice the phase problem for small molecules, their application to macromolecules is recent and still undergoing strong development. The fundamentals of the methods are described: in particular it is shown how the methods can be optimized for powder, neutron or electron data, and how they can be integrated with isomorphous replacement, molecular replacement and anomalous dispersion techniques. Maximum Entropy methods are also described and discussed. Sets of test structures are used to verify, throughout the various chapters, the mathematical techniques there described and to provide practical examples of applications. This book will appeal to a wide variety of readers - offering both a comprehensive description of direct methods in crystallography and an invaluable reference tool. The first three chapters can be considered as an introduction to the field, with sufficient material to constitute a university course and for allowing the expert use of most direct methods programs. Subsequent chapters are aimed at graduate students and working crystallographers. Basic results are described and discussed in the main body of the text, while the appendices compliment these with in depth mathematical details. The quoted literature is extremely wide and the interested reader can find suggestions for future work and further reading throughout the book.

SOMMARIO

1 - Wilson statistics1.A - About pseudosymmetries1.B - Fourier series of representation1.C - A modified Wilson plot procedure2 - Structure invariants and semi-invariants and the origin problem3 - Triplet invariant estimation and classical direct phasing procedures3.A - Other multi-solution methods4 - Direct methods and real space properties4.A - Direct methods and Patterson map properties: additional approaches4.B - Estimating structures semi-invariants from Harker sections4.C - Patterson deconvolution methods5 - The method of joint probability distributions5.A - P(E) and the saddle point method6 - Representations of structure invariants and semi-invariants6.A - Two algebraic propositions7 - The probabilistic estimation of triplet invariants7.A - The probabilistic estimation of quartet invariants8.A - Mathematical derivation of the phase relationship8.B - Mathematical derivation of the sign relationship8.C - Special quartets9 - The probabilistic estimation of quintet invariants10 - The probabilistic estimation of 1- and 2- phase structure semi-invariants10.A - Some mathematical details about the (1 estimates11 - Probabilistic determinantal approaches12 - Phasing neutron and electron data12.B - About HREM image formation13 - Direct phasing from powder data14 - Macromolecular crystallography techniques and traditional direct methods14.A - Crick and Magdoff relation14.B - Protein phase estimate incorporating the treatment of errors14.C - Solvent flattening14.D - About Fourier synthesis of large use in macromolecular crystallography14.E - Solvent content according to Matthews14.F - Ab initio calculation of low-resolution envelopes15 - The integration of direct methods with isomorphous replacement techniques15.A - Karle's Algebraic rule Riso15.B - About local scaling16 - The integration of direct methods with anomalous dispersion techniques16.A - Probabilistic treatment of the errors in the SIRAS case16.B - Coefficients in the distribution16.C - The maximal SAS principle17 - Molecular replacement techniques and direct methods

AUTORE

Professor Carmelo Giacovazzo, Professor of Mineralogy, Dipartemento Geomineralogico, Universitá di Bari, Via Orabona, 4 70125 Bari, Italy. Tel: 0039 80 5442590. Fax: 0039 80 5442591. Email: giacovazzo@area. ba.cnr.it

ALTRE INFORMAZIONI

• Condizione: Nuovo
• ISBN: 9780198500728
• Collana: International Union of Crystallography Monographs on Crystallography
• Dimensioni: 241 x 51.0 x 162 mm Ø 1353 gr
• Formato: Copertina rigida
• Illustration Notes: 8 halftones, 226 line drawings
• Pagine Arabe: 792