Chimera provides a graphical interface to running the program Modeller, either locally or via a web service hosted by the UCSF RBVI. Two types of calculations are available:

• Comparative (homology) modeling. Theoretical models of a protein target are generated using at least one known related template structure and a target-template sequence alignment. There are several ways to generate these inputs in Chimera. See also the Comparative Modeling tutorial.
  
  
• Building parts of a protein without using a template. Missing segments can be built de novo, or existing segments refined by generating additional possible conformations.

Peroxiredoxins are enzymes that help cells cope with stressors such as high levels of reactive oxygen species. The image shows a decameric peroxiredoxin from human red blood cells (Protein Data Bank entry 1qmv), styled as a holiday wreath.

See also the RBVI holiday card gallery.

(More samples...)