Chapter

Chapter 5.2 Crystal-density measurements

Crystallography of biological macromolecules

Second Online Edition (2012)

Part 5. Crystal properties and handling

  1. E. M. Westbrook

Published Online: 14 APR 2012

DOI: 10.1107/97809553602060000817

International Tables for Crystallography

International Tables for Crystallography

How to Cite

Westbrook, E. M. 2012. Crystal-density measurements. International Tables for Crystallography. F:5:5.2:152–157.

Author Information

  1. Molecular Biology Consortium, Argonne, Illinois 60439, USA

Publication History

  1. Published Online: 14 APR 2012

Abstract

Crystal-density measurements may be necessary to define a crystal’s molecular-packing arrangement, particularly when a crystal has an unusual packing density (very dense or very open); when there are a large number of subunits in the crystallographic asymmetric unit; when the structure consists of heterogeneous subunits, so the molecular symmetry or packing is uncertain; and for crystals of nucleic acids, nucleic acid/protein complexes and viruses. Topics covered in this chapter include: solvent in macromolecular crystals; the Matthews number; algebraic concepts related to crystal density; experimental estimation of hydration; and methods for measuring crystal denisty. A discussion of how to handle solvent density is also given.

Keywords:

  • Archimedes’ method;
  • Matthews number;
  • crystal-density measurement;
  • flotation method;
  • gradient-tube method;
  • estimation of hydration;
  • immersion microbalance;
  • pycnometry;
  • solvent;
  • solvent density;
  • tomographic crystal-volume measurement;
  • volumenometry