I have visited PDB (https://www.rcsb.org) and entered the PDB code 1TTA into the search line. Then I used the 3D view tab in order to draw a topology diagram of either one of the subunits. How would I classify this protein as an α, a β, an α/β or an α + β protein?
Is there a way to get the topology diagram of a protein at PDB from the viewer that shows the 3D structural model by default?
For that purpose I usually use PDBsum which has a 'Protein' tab for each PDB entry that includes protein:
The page under that tab also shows the wiring diagram illustrating the topology on the left side.
The architecture classification is included under the 'Protein' tab as well, which comes from the same source as the information that Mensur Dlakic (@Mensur ) directed you to at the PDB.