This could allow for more efficient determination of biological activities such as chemotaxis of PMNLs, mast cell degranulation, antibiosis, and even more potent analogs of kinins. The mathematical model used in the present investigation see more may also be applied to other biological systems that involve peptide components, and other different and physicochemical parameters may be included in the analysis in addition to, or as a substitute for the more common parameters used here. This research was supported by grants from FAPESP

(BIOprospecTA Proc. 04/07942-2, 06/57122-6) and INCT-Imunologia. M.S.P. is a researcher for the Brazilian Council for Scientific and Technological Development (CNPq). “
“Ureases

(EC 3.5.1.5) are nickel-dependent enzymes that catalyze urea hydrolysis into ammonia and carbon dioxide, and are synthesized by plants, fungi and bacteria [13] and [20]. Urease of jackbean (Canavalia ensiformis) seeds was the first enzyme ever to be crystallized [41], consisting of a hexamer of a single chain of 840 amino acid residues, with a molecular mass of 97 kDa [16], [20] and [38]. It has been postulated that in plants these IWR-1 concentration proteins contribute to the bioavailability of nitrogen and participate in defense mechanisms [12] and [16]. C. ensiformis produces several urease isoforms: the more abundant jackbean urease (JBURE-I), and two less abundant proteins, canatoxin (CNTX) [17] and JBURE-IIB [26]. CNTX-like proteins and urease accumulate in the mature seed, consistent with the proposed defense role associated with both insecticidal [40] and fungicidal properties [7] and [26]. Insecticidal activity of Jackbean urease depends mostly on the release of an entomotoxic peptide formed by proteolytic enzymes upon ingestion by the insect [15]. This peptide, Pepcanatox, was characterized and based on its sequence,

a recombinant peptide named Jaburetox-2EC was produced using the corresponding sequence of the urease isoform JBURE-II as template [27]. This peptide has 93 amino acids and its toxicity to Adenosine triphosphate several insects, including some species that were not affected by the native urease, has been demonstrated [40]. CNTX was the first urease shown to inhibit the radial growth of several filamentous fungi [29]. In 2007, Becker-Ritt et al. [7] reported the fungicidal activity of the embryo specific urease from Glycine max (soybean), the major urease from C. ensiformis and of a bacterial urease from Helicobacter pylori, regardless of their ureolytic activity, toward different phytopathogenic fungi. Urease from other sources also display fungicidal activity, such as the cotton (Gossypium hirsutum) seed urease [23] and the recombinant JBURE-IIb apourease from C. ensiformis [26].