Some proteins are "activated", like fibrinogens; they are turned into fibrins by thrombins, and then the fibrins can aid in blood clotting.
Are fibrinogens and fibrins the same molecule, just in different states? If so, are all "-ogen" ending proteins and their activated forms the same as well?
If they are different molecules, why do us even bother to convert a protein into anotherto work, instead of simply activating a protein?