Data processing

Techniques are described for the autoindexing of X-ray diffraction oscillation patterns and for the relative scaling of a series of such patterns to form a complete three-dimensional data set.

Cool data: qu­antity AND quality

Ways of optimizing X-ray cryo-data quality and quantity are discussed. The possible advantages/disadvantages of collecting X-ray data at 30 K instead of 100 K are also considered.

Macromolecular crystallography with a third-generation synchrotron source

Key features of the applications of the macromolecular crystallography beamlines at the ESRF are described.

Matching X-ray source, optics and detectors to protein crystallography requirements

Properties such as the required size, divergence, wavelength spread and intensity of the X-ray beam, together with the size and resolution of the detector, are derived from the properties of protein crystals and their diffraction patterns.

Experiences with CCD detectors on a home X-ray source

Charge-coupled device detectors are compared with other commercially available detectors and their use with home X-ray sources is discussed.

Experiences and expectations of a novel X-ray microsource with focusing mirror. I

The performance of the novel MicroSource X-ray generator is analysed and predictions are made for alternative designs of focusing optics. Relative performance of this microfocus tube and an optimized mirror system become increasingly advantageous with the study of ever-smaller crystals.

Optics systems for the home laboratory: caveat emptor

A detailed comparison of usable flux, spectral purity, divergence, beam profile and data quality for home-laboratory X-ray optics systems (total-reflection mirrors and multilayer monochromators) is presented.

The Rossmann Fourier autoindexing algorithm in MOSFLM

A one-dimensional FFT indexing routine developed previously is discussed with particular reference to its implementation in MOSFLM. The method has been shown to be robust and reliable even for unfavourable test images.

Integration of macromolecular diffraction data

Equations are derived for the summation integration and profile-fitted estimates of diffracted intensities and their standard errors. The advantages of profile fitting are discussed.

Data-collection strategies

The optimal strategy of collecting X-ray diffraction data from macromolecular crystals using the rotation method is discussed in both quantitative and qualitative aspects.

The finer things in X-ray diffraction data collection

The expectations and consequences of the processing of diffraction images with thick and thin rotation-angle increments are discussed. The d*TREK suite for processing images is briefly introduced.

MAD data collection – current trends

An outline of the steps involved in a MAD experiment are described, as well as recent experiences in ultrafast data collection.

New processing tools for weak and/or spatially overlapped macromolecular diffraction patterns

Deconvolution of overlapped spots, careful integration of weak spots and the use of statistical analysis tools are shown to improve the data quality of monochromatic data sets. The described techniques have been implemented in the integration software PrOW.

Complementing crystallography: the role of cryo-electron microscopy in structural biology

Cryo-electron microscopy cryo-EM) and crystallography are complimentary tools now available to the structural biologist. A brief discussion of the problems faced, and the advantages of cryo-Em and three-dimensional image reconstruction, along with three case studies, will be discussed.

Analysis and characterization of data from twinned crystals

The detection and analysis of diffraction data from twinned macromolecular crystals is discussed, as is the recovery of useful data from these crystals.

Detecting outliers in non-redundant diffraction data

Although it is better, if possible, to collect highly redundant diffraction data, the most damaging outliers can be detected using structure-factor probability distributions.

Protein microcrystals and the design of a microdiffractometer: current experience and plans at EMBL and ESRF/ID13

Experiments with macromolecular microcrystals at the EMBL/ESRF have shown that this technique offers several advantages. A custom-designed microdiffractometer is being built to ease microcrystal handling.

Some notes on choices in data collection

This paper presents a series of questions which should be considered in planning a data-collection experiment.