RasMol is freeware for the display of chemical structures. It uses coordinates from PDF to generate the images. You should print a copy of the documentation so that you know some of the cool things RASMOL can do!
       VMD, while a bit more cumbersome to use, is a modern piece of software that has some nice features. It too is freeware.

       There are a number of sites online that deal with specific classes of enzymes

       Kinases
       Proteases
       Restriction nucleases

       ExPASy has a page with information on general enzymes

       The National Center for Biotechnology Information has a number of useful tools for the analysis of DNA sequences. We will use BLAST.

       If you are interested in forensic applications of DNA analysis, look at the Innocence Project web site.