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This book aims to explain how and why the detailed three-dimensional architecture of molecules can be determined by an analysis of the diffraction patterns obtained when X rays or neutrons are scattered by the atoms in single crystals. Part 1 deals with the nature of the crystalline state, diffraction generally, and diffraction by crystals in particular, and, briefly, the experimental procedures that are used. Part II examines the problem of converting the experimentally obtained data into a model of the atomic arrangement that scattered these beams. Part III is concerned with the techniques for refining the approximate structure to the degree warranted by the experimental data. It also describes the many types of information that can be learned by modern crystal structure analysis. There is a glossary of terms used and several appendixes to which most of the mathematical details have been relegated.

Outline of Crystallography for Biologists is intended for researchers and students in the biological sciences who require an insight into the methods of X-ray crystallography without needing to learn all the relevant theory. The main text is purely descriptive and is readable by those with minimal mathematical knowledge. Some mathematical detail is given throughout in boxes, but these can be ignored. Theory is limited to the essentials required to comprehend issues of quality. There is an extensive reference section and suggestions for further reading for those who wish to delve deeper. The first part 'Fundamentals' presents the underlying ideas which allow x-ray structure analysis to be carried out and provides an appropriate background to courses in structural determination. The second part 'Practice' gives more information about the procedures employed in the course of crystal structure determination. The emphasis is on the quality measures of X-ray diffraction analysis to give the reader a critical insight into the quality and accuracy of a structure determination and to enable the reader to appreciate which parts of a structure determination may have caused special difficulty. There is no pretence of completeness and many matters discussed in standard crystallography texts are deliberately omitted. However, issues not brought out in the standard texts are discussed, making it a useful resource for non-practising crystallographers as well.

Modern crystallographic methods originate from the synergy of two main research streams, the small-molecule and the macro-molecular streams. The first stream was able to definitively solve the phase problem for molecules up to 200 atoms in the asymmetric unit. The achievements obtained by the macromolecular stream are also impressive. A huge number of protein structures have been deposited in the Protein Data Bank. The solution of them is no longer reserved to an elite group of scientists, but may be attained in a large number of laboratories around the world, even by young scientists. New probabilistic approaches have been tailored to deal with larger structures, errors in the experimental data, and modest data resolution. Traditional phasing techniques like ab initio, molecular replacement, isomorphous replacement, and anomalous dispersion techniques have been revisited. The new approaches have been implemented in robust phasing programs, which have been organized in automatic pipelines usable even by non-experts. Protein structures, which 50 years ago could take months or even years to solve, can now be solved in a matter of hours, partly also due to technological advances in computer science. This book describes all modern crystallographic phasing methods, and introduces a new rational classification of them. A didactic approach is used, with the techniques described simply and logically in the main text, and further mathematical details confined to the Appendices for motivated readers. Numerous figures and applicative details illustrate the text.