Inhibition of digestive trypsins by plant Kunitz proteins reduces the viability of Spodoptera cosmioides larvae

The acquired resistance by insects and the harmful environmental effects of chemical pesticides have encouraged the search of new tools for proper pest management. Among them, the use of protease inhibitors (PIs) obtained from plants has gained interest because they are a natural system against herbivory, are organic molecules with higher specificity and have the potential to cause less damage to nature. The aim of this work was to characterise the inhibitory potential of the proteins ApTI (Adenanthera pavonina trypsin inhibitor) and ILGA (Inga laurina trypsin inhibitor) on the digestive trypsins of Spodoptera cosmioides through molecular docking, enzymatic kinetics and biological survival analyses. The docking between trypsins and inhibitors was performed using the program CLUSPRO; the inhibitory constant Ki and the inhibition type were determined through chromogenic assays. In order to analyse survival, several concentrations of ApTI and ILTI inhibitors were included in the artificial diet of neonatal larvae. In this study, we determined that ILTI binds to the active site of the trypsins with a specificity similar to its natural substrate, whereas APTI showed that the inhibitor reactive site is not in contact with the trypsins catalytic site. The ILTI and APTI inhibitors were characterized as competitive and uncompetitive tight‐binding inhibitors, respectively. The survival curves obtained using Kaplan–Meier estimators indicated that the lowest percentage survival (20%) for all inhibitors tested was obtained using 1.0% doses at a development time of less than 20 days. We concluded that ILTI and APTI present biotechnological potential as agents against phytophagous Lepidoptera insects, inhibiting trypsins through tight‐binding inhibition, with competitive and non‐competitive mechanisms, respectively. The effect of ApTI and ILTI on the development of S. cosmioides larvae is shown to be toxic.     

Morphological and anatomical changes in soybean roots subjected to indole-3-acetic acid and tryptophol: indole compounds present in plant auxin metabolism

The auxin metabolism is practically elucidated, and the compounds that are part of the biosynthesis are well characterized, but the indole-3-ethanol or tryptophol, a molecule that has a regulatory position in the indole-3-acetic acid biosynthesis, still represents a gap in the understanding of this pathway. We examined the hypothesis that tryptophol present the function of plant growth regulation on soybean root development. We evaluated two doses of auxin and two doses of tryptophol (100 e 200 mg L^??1), respectively, beside a control treatment (water), via leaf application, in soybean plants under V1–V2 phonological stages. After 18 days of application, the roots were collected for their volume and area measurement, thereafter small segments (0.5 cm of length), were collected at 1 cm below the root-collar, for anatomical analysis. We observed that the control showed greater area and root volume, but using 200 mg L^??1 auxin and 100 mg L^??1 tryptophol led to a radial increase of roots with significant increases in width radius vascular and cortical parenchyma. These results suggest that the application of both compounds had a potential of modify the vascular and ground tissues in soybean roots, which may be beneficial for the development of plants.     

Lignin peroxidase isoforms from Streptomyces viridosporus T7A: are they a monomer based structure?

Five fractions with lignin peroxidase activity were isolated by FPLC-Mono Q from a Streptomyces viridosporus culture. F4 and F5 showed the highest specific activity and degree of protein homogeneity by chromatofocusing, IEF- and gradient-PAGE. The individual analysis of F4 and F5 by FPLC-Superdex 75, showed MW that were multiples to each other (68,000; 23,000; 12,000), although by SDS PAGE a sole MW of 13,500 was obtained, indicating a monomer based structure. The amino-acid composition of F5 showed absence of sulfur amino acids.     

Characterization of recombinant Desulfovibrio gigas ferredoxin.

Dg ferredoxin gene was cloned using the polymerase chain reaction (PCR), inserted into vector pT7-7, and overexpressed in Escherichia coli (E. coli) grown in aerobic media. The recombinant protein is a dimer and contains a [3Fe-4S] cluster per monomer. EPR and (1)H NMR data of recombinant and wild-type protein are compared.