Cloning, purification and biochemical characterization of recombinant Cathepsin L from Takifugu rubripes and its role in taste formation

In recent years Takifugu rubripes has been increasingly popular among people base on its good taste. Cathepsin L was related to the formation of amino acids and small peptides. This study described the biochemical characterization of Cathepsin L and its role in the taste formation of Takifugu rubripes. Cathepsin L gene from Takifugu rubripes tissues was cloned successfully, and Cathepsin L with molecular masses of 46 kDa was isolated and enzymatically characterized. This enzyme reached its highest activity at 40 °C and pH 5.5. Cu²⁺ and Mn²⁺ ions reduced the activity of Cathepsin L, but Fe³⁺ and Ca²⁺ ions prominently increased its activity when the final concentrations of metal ions were 1 mM and 5 mM, respectively. The addition of phenylmethanesulfonyl fluoride gradually decreased the enzyme activity over 0.5 mM. 200–3000 KDa fraction from Takifugu rubripes muscle after Cathepsin L hydrolysis showed the stronger kokumi and umami taste, especially kokumi. In this study, the recombinant Cathepsin L from Takifugu rubripes could play a role in flavor formation and be applied in flavor studies through the degradation of animal proteins.