We can’t see them with our own eyes, but viewed by X-Ray diffraction, proteins exhibit exquisite diversity. You can get an X-Ray eye’s view of protein structures at National Center for Biological Information’s Cn3D database. Here’s how to access three- dimensional animated images of proteins from the database:
Click http://www.ncbi.nlm.nih.gov/Structure/CN3D/cn3dinstall.shtml to download the Cn3D-4.3.1_setup file (for Windows or Mac). The software will reside on your computer and will activate when you go to a macromolecule database search site.
Click http://www.ncbi.nlm.nih.gov/Structure/MMDB/docs/mmdb_search.html to enter the protein structure database (below):
The search example shown above for human insulin takes you to this link: http://www.ncbi.nlm.nih.gov/structure/?term=human+insulin&SITE=NcbiHome&submit
.x=12&submit.y=12 The website is shown below:
Click View in Cn3D for the desired protein. For human insulin see this:
To rotate the molecule, click View then Animation, then Spin… and enjoy!