Screening method for detecting proteases in plant latices

The latex of some plant families such as Apocynaceae, Asclepiadaceae, Asteraceae, Caricaceae, Convolvulaceae, Euphorbiaceae, and Moraceae contains endopeptidases. Nearly half of the commercially available enzymes are proteases, frequently used in food processing, tenderization of meat, brewing, cheese elaboration, bread manufacturing, leather and textile industries [1]. Proteolytic enzymes from plant latex have also received special attention in the pharmaceutical industry and biotechnology due to their property of being active over wide range of temperature and pH [2]. The search for a new protease is always on. For detecting proteolytic activity in plant latices we collected latex of 70 plants out of ten different plant families which are located in the Botanical Garden Berlin. To determine proteolytic activity we used the fluorogenic substrate BODIPY FL- casein (Moleculare Probes, Inc., USA) [3]. The change in fluorescence was compared to that produced by trypsin as standard; with a volume of 100µl of each trypsin concentration. The plants were divided into three groups; group I shows no proteolytic activity in the latex (32 plants), group II has its activity in the range of minimal detectable 5µg/ml and 2.5mg/ml trypsin (16 plants) and group III has a very strong proteolytic activity higher than 2.5mg/ml trypsin (22 plants). The latices of group III have the potential to be a new source of commercial available proteases.

References: 1. Patel, B.K., Jagannadham, M.V. (2003)J Agric Food Chem 51: 6326–34.

2. Dubey, V.K., Jagannadham, M.V. (2003) Phytochemistry 62:1057–71.

3. Menges, D.A. et al. (1997) Anal Biochem 251:144–147.