Sirius supports a variety of applications with a set of features that include
Building and editing chemical structures using a library of fragments
Protein structure and sequence alignment
Command line interpreter and scripting support fully compatible with existing RasMol scripts
Full support for molecular dynamics trajectory visualization
BLAST search directly in Protein Data Bank and Uniprot databases
Ability to move parts of the loaded data while freezing the rest
Interactive calculation of hydrogen bonding, steric clashes, Ramachandran plots
Support for all major structure and sequence formats
Bundled POV-Ray for creating photorealistic images
Integrated selection and coloring across individual visualization components
Sirius is based on molecular graphics code and data structures developed as a part of Molecular Biology Toolkit.