Catalyzes the deacylation of 7 beta-(4-carboxybutanamido)cephalosporanic acid (glutaryl-7-aminocephalosporanic acid or GL-7-ACA) to 7-aminocephalosporanic acid (7-ACA). (7R)-7-(4-carboxybutanamido)cephalosporanate + H2O = (7R)-7-aminocephalosporanate + glutarate Heterotetramer of two alpha and two beta subunits processed from the same precursor. By glutaric acid. Belongs to the peptidase S45 family.