Finally let's have a quick look at one of the protein structure classification schemes you heard about in lecture 3. CATH is a hierarchical classification of protein domain structures, which clusters proteins at four major levels: Class (C), Architecture (A), Topology (T) and Homologous superfamily {H). Go to the CATH website by clicking on this link .
Under 'Using CATH' first click on the 'Browse' link. This will allow you to explore the hierarchy from the top (Class) level (mainly alpha, mainly beta, mixed alpha-beta and few secondary structures) down through architectures, topologies etc. How many architectures are there in the Mainly Alpha class?
Now go back to the home page and click on the 'Search' link under 'Using CATH'. This allows you to search for particular structures within the classification system. Type in the code corresponding to the protein you have been investigating and use the results to answer the questions. You can click on the link corresponding to the CATH code to get more information about what this means.
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