BRIEF COMMUNICATIONS Characterization of Proteases Secreted by Leek Roots 1

Some characteristics of rootsecreted protease s were studied. We measured their molecular weights and mechanism of BSA digestion in comparison to endogenous root proteases. We related these stud� ies to culture medium N composition. The seedlings of Allium porrum L. (cv. Bartek) were cultivated on MS medium, MS without inorganic nitrogen (MSIN), and MS without IN, but with 0.1% casein (MSIN + 0.1% casein). Electrophoretic study showed that rootsecreted proteases had one isoform with a mol wt of 45 kD, regardless of medium N composition. Difference in molecular weights of rootsecreted proteases and endogenous root proteases active under used conditions (>66 kD) provide us another strong evidence that rootsecreted proteases were not just leaking from the r oots, but they were secreted. Proteases exuded by roots degraded BSA in a similar way as endogenous proteases, with only one SDSPAGEdetectable product of degradation. Our results may be a powerful tool in the extraction and purification of these enzymes and also in proteomic studies.