How many different polypeptides could be produced for a protein that is 180 amino acids in length? Do you expect to find all these possible protein sequences produced in living systems?
Knowing there at 20 different possible amino acids that can be used for each polypeptide position, I would say there are 3600 possible different polypeptides that could be produced. I don't think you would find all these protein sequences produced in living systems but I'm not sure why.