---
id: mmcif-pdbx
version: "2.1.0"
license: CC0-1.0
license_treatment: permissive
maintenance: active
---

# mmcif-pdbx — Python utilities for PDBx/mmCIF storage model

License: permissive · Maintenance: active · Downloads: 429.4K/mo

## What it is and what it does

mmcif-pdbx is a lightweight, pure-Python library for working with PDBx/mmCIF molecular structure files—the standard format used by the Protein Data Bank to store macromolecular structure data. It provides utilities to read and parse these files into Python objects, making structural biology data accessible without compiled dependencies.

The package is derived from the official mmCIF examples but prioritizes simplicity and PEP8 compliance over the feature completeness of the canonical py-mmcif package. It has no runtime dependencies, making it easy to integrate into projects that need basic mmCIF functionality. It is actively maintained and supports modern Python versions.

Use it for:

- Parse PDB structure files in mmCIF format for structural biology analysis pipelines.
- Extract molecular coordinates and metadata from PDBx files in research or educational contexts.
- Build lightweight bioinformatics tools that need mmCIF support without C/C++ acceleration overhead.
- Integrate mmCIF data handling into Python applications where dependency minimalism is important.
- Prototype or test structural data workflows before committing to a heavier framework.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides a pure Python interface to read, parse, and work with PDBx/mmCIF molecular structure data files from the Protein Data Bank.

Yes, if you need basic mmCIF parsing in pure Python with no external dependencies. The permissive license, active maintenance, and support for current Python versions make it a low-risk choice. Choose the canonical py-mmcif package instead if you need advanced features or performance optimization for large-scale structure processing.

## Install

pip install mmcif-pdbx
uv add mmcif-pdbx
poetry add mmcif-pdbx

## Installing mmcif-pdbx

Before you install: Low friction installation with no runtime dependencies. Actively maintained with recent releases; supports current Python versions (3.10–3.13). Repository shows modest but steady activity.

License in practice: Licensed under CC0-1.0 (public domain equivalent), permissive treatment. No restrictions on use, modification, or redistribution for any purpose.

Quickstart:

pip install mmcif-pdbx

import mmcif.io
reader = mmcif.io.PdbxReader('structure.cif')
reader.read()

Requires Python 3.10 or later.

Verify before relying:

- Whether the package's API has stabilized since version 2.0 or if further breaking changes are expected.
- Performance characteristics when parsing large mmCIF files compared to the canonical py-mmcif package.

## Package facts

- License: CC0-1.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 429.4K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

mmcif pdbx parser, protein structure file format, pdb data parsing, molecular structure data, mmcif dictionary, pdbx utilities, structural biology data, structural-biology, bioinformatics, pure-python

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