CCP4

CCP4 stands for Collaborative Computational Project Number 4. It is a suite of software tools for macromolecular X-ray crystallography that provides an integrated, validated set of programs for data processing, phasing, model building, refinement, and validation of atomic models. The project emphasizes interoperability, documentation, and reproducibility across different steps of structure determination.

Origin and governance: Initiated by a collaboration among UK universities and research institutes with support from national funding agencies, CCP4 has grown into an internationally used community resource. The software is distributed free for academic use and is maintained by a formal CCP4 consortium, which coordinates development, validation, and training through annual meetings and online resources.

Key components and workflow: The CCP4 suite bundles numerous programs used in typical crystallographic work. Examples include REFMAC5 for refinement, MOLREP and Phaser for molecular replacement, Buccaneer for automated model building, and visualization tools such as Coot. It provides graphical interfaces (for example CCP4i and its successors) and command-line tools, enabling data processing, phasing, density modification, model building, refinement, and validation within a common framework.

Impact and use: CCP4 has been a central platform in structural biology, contributing to thousands of deposited structures and helping standardize practices in data handling and reporting. The project continues to evolve with web-based access through CCP4 Cloud and ongoing training materials, ensuring compatibility with modern operating systems and hardware.