RESUMO
BACKGROUND: The achenes/seeds of endemic jelly fig (Ficus pumila var. awkeotsang) fruit have been applied to prepare a traditional beverage in Taiwan. Upon fruit harvest, jelly fig latex exuded from stalks was discarded. Protease activity was monitored in its latex. Proteases capable of hydrolyzing proteins have many application aspects based on diverse characteristics. Commercial plant proteases are frequently from latex. RESULTS: The latex protease of jelly fig, termed FaFicin, was purified to homogeneity with a molecular mass of ~32 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. According to liquid chromatographic-tandem mass spectrometric analyses, the expected protein band of protease was matched to ficin A, ficin B or chymopapain from common fig or papaya. Iodoacetamide, an inhibitor of cysteine protease, inhibited its protease activity completely. Hence FaFicin was identified as a papain-like cysteine protease (PLCP), exhibiting more than 80% and 70% activity as assayed at pH 5-8 and 40-70 °C, respectively. It maintained ~89% of initial activity after 120 min at 55 °C and pH 7. Moreover, FaFicin could degrade the myosin and actin of meat, and clot milk. CONCLUSION: The ficin FaFicin was obtained, purified and identified as a PLCP member from agricultural waste: jelly fig latex. It possessed activity under a wide range of pH values and temperature, and exhibited excellent thermostability. Based on its initial evaluation as a meat tenderizer and milk clotting reagent, the application of FaFicin was possible, which may extend utilization of jelly fig. © 2022 Society of Chemical Industry.
