**7. Mechanism of action for insecticidal property in leguminous plant**

Ureases from plants such as *G. max* (soy bean) and jack bean (JBU and *canatoxin*) are discovered to exhibit insecticidal activity in insects with cathepsin B-based (cysteine protease) and cathepsin D-based (aspartyl protease) digestive system. But no effect was observed in insects that relay on digestive enzymes which are trypsin-like [124, 125]. It is interesting to note that, no change was seen in the insecticidal effects of *canatoxin* and *G. max* ureases was after the enzyme was treated with an irreversible inhibitor of ureolytic activity, which indicate that ureolytic and insecticidal activities are not related [100]. In canatoxin, it was shown that its entomotoxic effect depends on an internal 10-kDa peptide (called pepcanatox), which is released by canatoxinhydrolysis by cathepsins in the digestive system of insects that are susceptible. Nonetheless, a 13-kDa recombinant peptide named jaburetox-2Ec, analog to pepcanatox, was cloned in *Escherichia coli* and was discovered to have insecticidal activity [126]. But with ureases from plant, there was no insecticidal activity seen in bacterial (*Bacillus pasteurii*) urease [100] and it was proposed that the entomotoxic peptide released from canatoxin by insect cathepsins is not present in ureases from microbes due to the subunit structure which is made up of two or three chains [100] and peptides that links and connect the different chains exhibit the insecticidal activity. Canatoxins has been studied extensively in several applications including industrial, agricultural, and medical [127]. Insect pest are the main cause of damage in agriculture having negative effect on commercially important crops globally. Having transgenic crops with intrinsic resistance to pest propose an alternative that is promising for chemical pesticides to prevent the crop losses [128]. Since plant ureases exhibit insecticidal property, to know their threedimensional structure and the structural basis of their mechanism of its endomotoxic peptide could be used effectively for the development of transgenic plants that are resistant to insects. From the industrial point of view, a large number of research papers have been published four decades ago in legumes urease immobilization studies. Legumes urease structural integrity and important resistance to chemical and thermal deactivation have been studied extensively for immobilization studies. Based on these facts, the present study reveals some details of leguminous canatoxin urease, which may be utilized by researchers to design better carriers for enzyme immobilization and areas by utilizing these plants.
