Abstract: Takifugu rubripes has a delicious taste. To date, a series of umami peptides have been separated and identified from T. rubripes, but their formation mechanism is not yet clear. Cathepsin L degrades myofibrillar protein and troponin during muscle degradation and thus plays an important role in the flavor formation. This study aimed to elucidate the possible mechanism of flavor peptide formation. We obtained a 1 336 bp sequence of cathepsin L gene from the NCBI database, and extracted RNA from the muscle of T. rubripes, and then reverse-transcribed it into cDNA. PET-28a (+) as the expression vector and E. coli BL21 as engineering bacteria was used to clone and express the cathepsin L gene. Recombinant cathepsin L was obtained with a molecular mass of 36 kD, and the E. coli expression system was also successfully validated. This study can provide useful information for further studies on enzymatic characteristics and of cathepsin L and its role in taste formation in T. rubripes.

Key words: Takifugu rubripes, cathepsin L, flavor peptide, E. coli expression system