Abstract: A polynucleotide, encoding an amino acid sequence, encoding an oxidoreductase, that is ?50% identical to an amino acid sequence of SEQ ID NO:1 (Geobacillus sp. PA9), SEQ ID NO:3 (Thermus thermophilus), SEQ ID NO:4 (Streptomyces globisporus), SEQ ID NO:5 (Clostridium aminobutyricum), SEQ ID:6 (Burkholderai cepacia), SEQ ID NO:8 (Oscillatoria sp. PCC 6506), or SEQ ID NO:9 (Paraburkholderia phymatum). The polynucleotide has an amino acid exchange in one or more of positions 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214 of SEQ ID NO:1, or at a corresponding position of the amino acid sequence of SEQ ID NO:3, SEQ ID NO:4, SEQ ID:5, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:9.

Abstract: The present invention provides methods for the production of recombinant polypeptides having serine protease activity, polypeptides obtainable by such methods and use of said polypeptides in medicine, cosmetics and industry. In particular, the invention provides recombinantly expressed mutants of trypsin I from Atlantic cod, which mutants exhibit improved stability and/or catalytic properties relative to the wildtype trypsin purified from cod.