Characterization of two extracellular proteases fromLeuconostoc oenos.

Two extracellular proteolytic activities were characterized fromLeuconostoc oenos isolated from Argentinian wines. Both activities were maximal with autoclaved grape juice as substrate. The temperature and pH optima for the two proteolytic activities were different (30 and 40°C, and pH 4.0 and 5.5, respectively). Both enzymes were thermostable and their activities were unaltered by heating at 70°C for 15 min. Metal ions were not required for the activities. Neither enzyme appeared to be a serine protease but both were strongly inhibited by cysteine and β-mercaptoethanol, indicating the involvement of disulphide bridges.