Hydrolyzes the polyglutamate sidechains of pteroylpolyglutamates. Progressively removes gamma-glutamyl residues from pteroylpoly-gamma-glutamate to yield pteroyl-alpha-glutamate (folic acid) and free glutamate (PubMed:11005824, PubMed:8816764). May play an important role in the bioavailability of dietary pteroylpolyglutamates and in the metabolism of pteroylpolyglutamates and antifolates. (6S)-5,6,7,8-tetrahydrofolyl-(gamma-L-Glu)(n) + (n-1) H2O = (6S)-5,6,7,8-tetrahydrofolate + (n-1) L-glutamate Homodimer. While its intracellular location is primarily the lysosome, most of the enzyme activity is secreted. Identified by mass spectrometry in melanosome fractions from stage I to stage IV. Belongs to the peptidase C26 family.