Trypsin from Pacifastacus leniusculus hepatopancreas: Purification and cDNA cloning of the synthesized zymogen

Trypsin was purified from crayfish, Pacifastacus leniusculus, hepatopancrea s, and the gene that encoded this enzyme was cloned from a hepatopancreas c DNA library. Crayfish trypsin is synthesized as a zymogen according to the sequence of the putative precursor peptide. The authenticity of the trypsin ogen is supported by the deduced amino acid sequence and confirmed by the N -terminal amino acid sequence of the mature protein. The enzyme has feature s characteristic of a trypsin, such as a specific binding pocket. Sequence comparison shows that crayfish trypsin is similar to those of other species , with the exception that six cysteine residues present in vertebrates are missing. Some structural characteristics, such as the length of the signal peptide and a calcium binding site, are similar to bacterial trypsin.