The present invention provides An isolated polypeptide which has proline specific endoprotease activity, selected from the group consisting of:(a) a polypeptide which has an amino acid sequence which has at least 40% amino acid sequence identity with amino acids 1 to 526 of SEQ ID NO:2 or a fragment thereof;(b) a polypeptide which is encoded by a polynucleotide which hybridizes under low stringency conditions with (i) the nucleic acid sequence of SEQ ID NO:1 or a fragment thereof which is at least 80% or 90% identical over 60, preferably over 100 nucleotides, more preferably at least 90% identical over 200 nucleotides, or (ii) a nucleic acid sequence complementary to the nucleic acid sequence of SEQ ID NO:1.