Size and shape of protein molecules at the nanometer level determined by sedimentation, gel filtration, and electron microscopy.

Journal Article (Journal Article)

An important part of characterizing any protein molecule is to determine its size and shape. Sedimentation and gel filtration are hydrodynamic techniques that can be used for this medium resolution structural analysis. This review collects a number of simple calculations that are useful for thinking about protein structure at the nanometer level. Readers are reminded that the Perrin equation is generally not a valid approach to determine the shape of proteins. Instead, a simple guideline is presented, based on the measured sedimentation coefficient and a calculated maximum S, to estimate if a protein is globular or elongated. It is recalled that a gel filtration column fractionates proteins on the basis of their Stokes radius, not molecular weight. The molecular weight can be determined by combining gradient sedimentation and gel filtration, techniques available in most biochemistry laboratories, as originally proposed by Siegel and Monte. Finally, rotary shadowing and negative stain electron microscopy are powerful techniques for resolving the size and shape of single protein molecules and complexes at the nanometer level. A combination of hydrodynamics and electron microscopy is especially powerful.

Full Text

Duke Authors

Cited Authors

  • Erickson, HP

Published Date

  • May 15, 2009

Published In

Volume / Issue

  • 11 /

Start / End Page

  • 32 - 51

PubMed ID

  • 19495910

Pubmed Central ID

  • PMC3055910

International Standard Serial Number (ISSN)

  • 1480-9222

Digital Object Identifier (DOI)

  • 10.1007/s12575-009-9008-x


  • eng

Conference Location

  • England