3BF0 | C:56-178,C:221-318; D:56-178,D:221-318; A:56-178,A:221-318; B:56-178,B:221-318; C:319-432,C:499-551; A:319-432,A:499-549; B:319-432,B:499-549; D:319-432,D:499-549 | CRYSTAL STRUCTURE OF ESCHERICHIA COLI SIGNAL PEPTIDE PEPTIDASE (SPPA), NATIVE CRYSTALS |