Characterization of a Kunitz trypsin inhibitor with a single disulfide bridge from seeds of Inga laurina (SW.) Willd.

Inga laurina is a tree that belongs to the Mimosoideae sub-family of the Leguminosae. A protein inhibitor of trypsin (ILTI) was isolated from its seeds by ammonium sulphate precipitation, ion-exchange chromatography and rechromatography on an HiTrap Q ion-exchange column. By SDS-PAGE, ILTI yielded a single band with a Mr of 20 kDa with or without reduction. ILTI was found to be a single polypeptide chain containing 180 amino acids, the sequence of which was clearly homologous to the Kunitz family of serine protease plant protein inhibitors, and it also showed significant similarity to the seed storage proteins, sporamin and miraculin. However, ILTI displayed major differences to most other Kunitz inhibitors in that it contained only one disulfide bridge, and did not have two polypeptide chains as for the majority of other Kunitz inhibitors purified from Mimosoideae species. ILTI inhibited bovine trypsin with an equilibrium dissociation constant (K(i)) of 6 x 10(-9)M, but did not inhibit chymotrypsin, papain and alpha-amylase. Its amino acid sequence contained a Lys residue at the putative reactive site (position 64). ILTI was stable over a wide range of temperature and pH and in the presence of DTT.

Insecticidal and antifungal activity of a protein from Pouteria torta seeds with lectin-like properties.

This paper describes the purification and characterization of a novel protein from the seeds of Pouteria torta (family Sapotaceae). The protein was purified by a combination of gel filtration, ion-exchange, and reverse phase chromatographies. SDS-PAGE of the purified protein resulted in a single protein band of 14 kDa in the presence and absence of DTT. The lectin-like activity of pouterin was best inhibited by glycoproteins such as fetuin, asialofetuin, heparin, orosomucoid, and ovoalbumin. Pouterin inhibited the growth of the fungi Fusarium oxysporum and Colletotrichum musae and of the yeast Saccharomyces cerevisiae. The incorporation of pouterin into an artificial diet (final concentration = 0.12%, w/w) caused 50% mortality in larvae of the insect Callosobruchus maculatus, whereas 0.08% pouterin produced an ED50.

Purification and characterization of a lectin from Annona coriacea seeds.

A novel lectin, denominated ACLEC, was isolated from Annona coriacea seeds, belonging to the Annonaceae family. The lectin presented one protein band in SDS-PAGE of 14 kDa. Of the sugars tested, Dglucose and D-mannose were the best inhibitors. A search sequence database showed that ACLEC had homology with other plant lectins, belonging to leguminous lectin family.

Structural insights regarding an insecticidal Talisia esculenta protein and its biotechnological potential for Diatraea saccharalis larval control.

Talisin is a seed-storage protein from Talisia esculenta that presents lectin-like activities, as well as proteinase-inhibitor properties. The present study aims to provide new in vitro and in silico biochemical information about this protein, shedding some light on its mechanistic inhibitory strategies. A theoretical three-dimensional structure of Talisin bound to trypsin was constructed in order to determine the relative interaction mode. Since the structure of non-competitive inhibition has not been elucidated, Talisin-trypsin docking was carried out using Hex v5.1, since the structure of non-competitive inhibition has not been elucidated. The predicted non-coincidence of the trypsin binding site is completely different from that previously proposed for Kunitz-type inhibitors, which demonstrate a substitution of an Arg(64) for the Glu(64) residue. Data, therefore, provide more information regarding the mechanisms of non-competitive plant proteinase inhibitors. Bioassays with Talisin also presented a strong insecticide effect on the larval development of Diatraea saccharalis, demonstrating LD50 and ED50 of ca. 2.0% and 1.5%, respectively.

Bioinsecticidal activity of Talisia esculenta reserve protein on growth and serine digestive enzymes during larval development of Anticarsia gemmatalis.

Plants synthesize a variety of molecules to defend themselves against an attack by insects. Talisin is a reserve protein from Talisia esculenta seeds, the first to be characterized from the family Sapindaceae. In this study, the insecticidal activity of Talisin was tested by incorporating the reserve protein into an artificial diet fed to the velvetbean caterpillar Anticarsia gemmatalis, the major pest of soybean crops in Brazil. At 1.5% (w/w) of the dietary protein, Talisin affected larval growth, pupal weight, development and mortality, adult fertility and longevity, and produced malformations in pupae and adult insects. Talisin inhibited the trypsin-like activity of larval midgut homogenates. The trypsin activity in Talisin-fed larvae was sensitive to Talisin, indicating that no novel protease-resistant to Talisin was induced in Talisin-fed larvae. Affinity chromatography showed that Talisin bound to midgut proteinases of the insect A. gemmatalis, but was resistant to enzymatic digestion by these larval proteinases. The transformation of genes coding for this reserve protein could be useful for developing insect resistant crops.

Characterization of a saccharide-binding protein from Talisia esculenta seeds with trypsin inhibitory activity.

Some proteins exhibit characteristics that suggest they have a primary, if not an exclusive role in nutrient reserve storage. The best studied examples are the storage proteins that accumulate specifically in developing seeds. Some of these protein demonstrate biological activities that could contribute to resistance to pest, pathogens or abiotic stresses. In this study we present the biochemical characterization and cloning of the major protein from seeds of T. esculenta (Talisin), a member of the Sapindaceae family. The N-terminal sequence of the protein isolated was used to produce a degenerated primer. This primer allowed the amplification of the Talisin cDNA by RTPCR from mRNA of the T. esculenta seeds protein. The sequence analysis of the cloned cDNA, demonstrated a 756 bp sequence encoding a peptide of 198 amino acids. The deduced peptide presented high similarity to a typical VSP, the 22-kDa protein in lychee (73 %) and 50.0 % identity to Theobroma bicolor reserve protein. Identities of 52.0 % and 44.0 % to trypsin inhibitors from Treobroma mammosum and Populus tremula respectively. In conclusion, we may suggest that Talisin could be a seed storage protein with affinity properties, i.e. interacts with carbohydrates and trypsin enzyme.

Effect of the aqueous extracts of the seeds of Talisia esculenta and Sapindus saponaria on fall armyworm

The effect of aqueous extracts of Talisia esculenta (T.E.) and Sapindus saponaria (S.S.), were evaluated on the development and mortality of 8-14th day-life Spodoptera frugiperda, an important pest of maize. Corn leaves were dipped in the aqueous extracts (1 percent w/v) and offered as food to the caterpillars. The treated corn leaves with the extracts caused larval mortality (26.71 percent/T.E.; 63.3 percent/S.S.) and also showed effect on the larval weight (237.50 mg/T.E.; 86.65 mg/S.S.) when compared with the control (11.3 percent and 293.45 mg), mortality and larval weight, respectively. The electrophoresis with gelatin (0.1 percent) showed two very clear white areas (trypsin activity) in the caterpillars midgut of all the treatments. Only the caterpillar treated with S. saponaria presented significant differences, showing trypsin activity (10.59 percent). Sapindus saponaria appeared better than Talisia esculenta and showed good potential to be used as control agent for S. frugiperda.

Este estudo procurou avaliar o potencial inseticida dos extratos aquosos de sementes de Talisia esculenta (St. Hil.) Radlk (Pitombal) e Sapindus saponaria L. (Saboneteira), ambas da família Sapindaceae, sobre Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), importante praga da lavoura de milho. As folhas de milho foram imersas nos tratamentos com extratos aquosos (1 por cento p/v) e oferecidas como alimento para as lagartas. Os resultados do período larval tais como mortalidade e peso médio foram respectivamente: para S. saponaria 63,15 por cento, 86,65 mg; para T. esculenta 26,71 por cento, 237,50 mg e para o controle 11,3 por cento, 293,45 mg. A eletroforese com gelatina 0,1 por cento mostrou duas regiões brancas muito nítidas (atividade tríptica) no intestino médio das lagartas de todos os tratamentos. Somente as lagartas do tratamento S. saponaria, apresentaram diferenças significativas, com uma atividade tríptica 10,59 por cento menor.