As shown in Fig. 5, JBU (0.09 μM) inhibited the acidification produced by S. cerevisiae and C. albicans cells by 92% and 95%, respectively. Alignments of the sequences of ureases revealed the presence of homologous regions with plant antifungal proteins, such as pea defensins, phasein A (a chitinase of Phaseolus vulgaris cv. chick), thaumatin and antifungal peroxidases [28] ( Supplemental Figs. 1 and 2). Although the degree of homology of ureases with these antifungal proteins is not

high, it is noteworthy the fact that most of the homologous regions are close to each other, located in the alpha domain of JBU. This observation motivated the search of a putative antifungal domain in JBU. In a similar approach previously used to identify the insecticidal

domain of C. ensiformis ureases [11], [15] and [40], we tested different proteolytic enzymes (chymotrypsin, pepsin, trypsin and papain) for their ability to hydrolyze JBU producing antifungal GSK1349572 peptide(s). Among the enzymes tested, papain hydrolyzed JBU generating fungitoxic fragment(s) after 2 h at 37 °C, selleckchem pH 6.5, at an 1:10 enzyme/substrate ratio. Besides yeasts, JBU-derived peptides obtained by papain hydrolysis were also active against Mucor sp. and F. oxysporum, being more potent than the native protein ( Fig. 6, panels A–D). Tryptic peptides derived from JBU were also fungitoxic, however trypsin alone or products of its auto hydrolysis also presented inhibitory activity to some fungi, such as Mucor sp. without inhibiting others, like F. oxysporum. JBU samples hydrolyzed by papain were analyzed by SDS-PAGE in Tricine buffer, showing the disappearance of the JBU (∼100 kDa) band and the presence of smaller bands, particularly in the 10 kDa region (Fig. 6, panel E). Starting from 1 mg of JBU, the papain-hydrolyzed fraction containing peptides smaller than 10 kDa was desalted, lyophilized and analyzed to liquid chromatography coupled to mass spectrometry. Five peptides, corresponding to Isotretinoin 7.1% sequence coverage of JBU (Table 1), were identified. The sequences of these

peptides within JBU are highlighted in Supplemental Fig. 3. Interestingly, none of the peptides found matched any of the JBU regions that are homologous to the plant antifungal proteins shown in Supplemental Fig. 2, or showed homology to any other known antifungal proteins. No results were found searching these peptides against the Antimicrobial Peptide Database (APD2) [43]. Among the peptides identified, one (sequence in italics in Table 1) contained a partial sequence of the entomotoxic peptide Pepcanatox [29], which displays 10 kDa, similar to the most abundant peptides resulting from JBU hydrolysis by papain (Fig. 6, panel E). Based on these data, a possible antifungal activity of a recombinant peptide equivalent to Pepcanatox [10] was evaluated. The peptide used in this study, named Jaburetox, contains the same 93 amino acids sequence derived from JBU (shown in Supplemental Fig.