Average protein density is a molecular-weight-dependent function

Protein Sci. 2004 Oct;13(10):2825-8. doi: 10.1110/ps.04688204.


The mass density of proteins is a relevant basic biophysical quantity. It is also a useful input parameter, for example, for three-dimensional structure determination by protein crystallography and studies of protein oligomers in solution by analytic ultracentrifugation. We have performed a critical analysis of published, theoretical, and experimental investigations about this issue and concluded that the average density of proteins is not a constant as often assumed. For proteins with a molecular weight below 20 kDa, the average density exhibits a positive deviation that increases for decreasing molecular weight. A simple molecular-weight-depending function is proposed that provides a more accurate estimate of the average protein density.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Computational Biology / methods
  • Crystallography
  • Molecular Weight
  • Protein Conformation
  • Proteins / chemistry*
  • Ultracentrifugation


  • Proteins