John R. Helliwell studied physics at the University of York and obtained a PhD from the University of Oxford in 1978. For many years he was closely associated with the Synchrotron Radiation Source at Daresbury Laboratory, while also holding positions at the University of Keele, the University of York and the University of Manchester, where he is now an Emeritus Professor. His research has contributed to over 100 Protein Data Bank crystal structure depositions spanning enzymes, lectins and crustacyanins with ligands such as saccharides, carotenoids and metallodrugs or metalloimaging agents. In 2014 he was awarded the A. L. Patterson Award by the American Crystallographic Association and in 2015 he was awarded the Max Perutz Prize by the European Crystallographic Association. He is a Fellow of the American Crystallographic Association, a Fellow of the Institute of Physics, the Royal Society of Chemistry, and the Royal Society of Biology.

• Preface Acknowledgements About the author 1: Introduction 2: The physics of errors as illustrated by X-ray crystallography 3: History of the reliability of structure determination methods 4: Mass spectrometry 5: Structure validation approaches 6: Other validation tools: Round-robin projects 7: Similarities and differences in the probes used in structure determination 8: Fibre diffraction 9: Powder diffraction 10: Small-angle solution scattering 11: Electron microscopy (EM) 12: X-ray absorption spectroscopy (XAS) 13: NMR 14: EPR for metalloproteins 15: Combining methods for accuracy 16: Combining methods to span different length scales 17: Role of simulations of structural dynamics as a complement to experimental studies 18: Role of predictions as a grand challenge in biology: Protein fold prediction is solved 19: A new method: X-ray photon correlation spectroscopy (XPCS) to study biocondensed matter 20: Conclusions 21: Appendix A1: Bayesian reasoning in data analysis and model refinement Bibliography Abbreviations List Index