obsolete dipeptidyl-peptidase I activity true dipeptidyl-peptidase I activity This term was made obsolete because it represents a gene product. GO:0004214 OBSOLETE. Catalysis of the release of an N-terminal dipeptide, Xaa-Xbb from Xaa-Xbb-Xcc, except when Xaa is Arg or Lys, or Xbb or Xcc is Pro. molecular_function cysteine-type peptidase activity dipeptidyl-peptidase activity