Isolation of a novel peroxidase from French bean legumes and first demonstration of antifungal activity of a non-milk peroxidase

In Vitro Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Mangifera indica Aqueous Leaf Extract against Multidrug-Resistant Pathogens

An estimated 35% of the world’s population depends on wheat as their primary crop. One fifth of the world’s wheat is utilized as animal feed, while more than two thirds are used for human consumption. Each year, 17–18% of the world’s wheat is consumed by China and India. In wheat, spot blotch caused by Bipolaris sorokiniana is one of the major diseases which affects the wheat crop growth and yield in warmer and humid regions of the world. The present work was conducted to evaluate the effect of green synthesized silver nanoparticles on the biochemical constituents of wheat crops infected with spot blotch disease. Silver nanoparticles (AgNPs) were synthesized using Mangifera indica leaf extract and their characterization was performed using UV-visible spectroscopy, SEM, XRD, and PSA. Characterization techniques confirm the presence of crystalline, spherical silver nanoparticles with an average size of 52 nm. The effect of green synthesized nanoparticles on antioxidative enzymes, e.g., Superoxide dismutase (SOD), Catalase (CAT), Glutathione Reductase (GR), Peroxidase (POX), and phytochemical precursor enzyme Phenylalanine Ammonia-Lyase (PAL), and on primary and secondary metabolites, e.g., reducing sugar and total phenol, in Bipolaris sorokiniana infected wheat crop were studied. Inoculation of fungal spores was conducted after 40 days of sowing. Subsequently, diseased plants were treated with silver nanoparticles at different concentrations. Elevation in all biochemical constituents was recorded under silver nanoparticle application. The treatment with a concentration of nanoparticles at 50 pp min diseased plants showed the highest resistance towards the pathogen. The efficacy of the green synthesized AgNPs as antibacterial agents was evaluated against multi drug resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) and Gram-positive bacteria Methicillin resistant Staphylococcus aureus (n = 2). The results show promising antibacterial activity with significant inhibition zones observed with the disc diffusion method, thus indicating green synthesized M. indica AgNPs as an active antibacterial agent against MDR pathogens.

Purification and characterization of peroxidase from sprouted green gram (Vigna radiata) roots and removal of phenol and p-chlorophenol by immobilized peroxidase

BACKGROUND

Peroxidase activity was increased during germination of green gram and such an increase may have benefits in many physiological processes. The present study aimed to investigate the optimum conditions for the extraction, purification and characterization of peroxidase from the germinated green gram roots and also its application for the removal of phenols in water.

RESULTS

Peroxidase activity was increased by 300-fold in 5-day germinated green gram. Because the root was rich in peroxidase activity, peroxidase from roots was isolated and purified to homogeneity. The purified peroxidase showed a single band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis with a molecular weight of 50 kDa, an optimum pH of 5.5 and a pH stability ranging from 5 to 9. The enzyme had 50% residual activity at 70 °C. It catalyzed the oxidation of a variety of substrates. The K_m value of the enzyme was 1.28 mmol L^-1 for o-dianisidine and 0.045 mmol L^-1 for H₂ O₂ . The enzyme lost 100% activity in the presence of dithiothreitol and cysteine. The addition of copper ion increased the enzyme activity by three-fold. Both soluble and immobilized peroxidases removed more phenol than p-chlorphenol, whereas horseradish peroxidase removed more p-chlorphenol. Thus, the green gram root peroxidase showed good pH and temperature stability, as well as the ability to remove phenolic compounds from effluent.

CONCLUSION

Peroxidase with good thermal and pH stability was purified from germinated green gram roots and has the ability to oxidize phenolic compounds from waste water. © 2016 Society of Chemical Industry.

A novel peroxidase purified from Marsdenia megalantha latex inhibits phytopathogenic fungi mediated by cell membrane permeabilization

An antifungal class III peroxidase was purified from Marsdenia megalantha latex (named Mo-POX) using DEAE-cellulose and gel filtration chromatography on a Superose 12 HR 10/30 column. Mm-POX has an apparent molecular mass of 67.0kDa and a pI of 5.2, shares identity with other peroxidases, and follows Michaelis-Menten kinetics. It has a high affinity for guaiacol and hydrogen peroxide. The pH and temperature optima for Mm-POX were 5.0-7.0 and 60°C, respectively. The catalytic activity of Mm-POX was decreased in the presence of classic peroxidase inhibitors including azide, dithiothreitol, ethylenediamine tetraacetic acid, and sodium metabisulfite and high concentrations of Na⁺, Mn⁺, and salicylic acid. In contrast, Ca⁺ and Mg⁺, even at low concentrations, enhanced the Mm-POX enzymatic activity. This protein inhibited the germination of the conidia of the phytopathogenic fungi Fusarium oxysporum and Fusarium solani by acting through a membrane permeabilization mechanism. Mm-POX also induced oxidative stress in F. solani. Mm-POX is the first enzyme to be isolated from the M. megalantha species and it has potential use in the control of plant disease caused by important phytopathogenic fungi. This adds biotechnological value to this enzyme.

Transcriptome and proteome analyses provide insight into laticifer's defense of Euphorbia tirucalli against pests

The cytoplasm of laticifers, which are plant cells specialized for rubber production and defense against microbes and herbivores, is a latex. Although laticifers share common functions, the protein constituents of latexes are highly variable among plant species and even among organs. In this study, transcriptomic and proteomic analyses of Euphorbia tirucalli's (Euphorbiaceae) latex were conducted to determine the molecular basis of the laticifer's functions in this plant. The hybrid de novo assembly of Illumina mRNA-seq and expressed sequence tags obtained by Sanger's sequencing revealed 26,447 unigenes. A unigene similar to Arabidopsis embryo-specific protein 3 (AT5G62200), which is a PLAT domain-containing protein, and rubber elongation factor showed the highest expression levels. The proteome analysis, studied by liquid chromatography-mass spectrometry with the de novo assembled unigenes as the database, revealed 161 proteins in the latex, 107 of which were not detected in the stem. A gene ontology analysis indicated that the laticifer's proteome was enriched with proteins related to proteolysis, phosphatase, defense against various environmental stresses and lipid metabolisms. D-mannose-binding lectin, ricin (which lacked the N-terminal conserved ribosome-inactivating protein domain), chitinase and peroxidase were highly accumulated, as confirmed by two-dimensional polyacrylamide gel electrophoresis. Thus, the lectins and chitinase may be the major defensive proteins against pests, and the other defense-related proteins and transcripts detected in latex may work in coordination with them. Highly expressing unigenes with unknown functions are candidate novel defense- or rubber production-related genes.

Plant antifungal proteins and their applications in agriculture

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of a substantial portion of the crop every year. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low-molecular-weight secondary metabolites and proteins and peptides with antifungal activity. In this review, families of plant antifungal proteins (AFPs) including defensins, lectins, and several others will be summarized. Moreover, the application of AFPs in agriculture will also be analyzed.

Purification and characterization of a protein with antifungal, antiproliferative, and HIV-1 reverse transcriptase inhibitory activities from small brown-eyed cowpea seeds

A 36-kDa protein, with an N-terminal sequence highly homologous to polygalacturonase (PG) inhibiting proteins, was isolated from small brown-eyed cowpea seeds. The protein was unadsorbed on diethylaminoethyl cellulose but adsorbed on both Affi-gel blue gel and SP-sepharose. It inhibited mycelial growth in the fungus Mycosphaerella arachidicola with an half-maximal (50%) inhibitory concentration (IC50 ) of 3.3 µM. It reduced [methyl-(3) H] thymidine incorporation into MBL2 lymphoma and L1210 leukemia cells with an IC50 of 7.4 and 5.4 µM, respectively. It inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase with an IC50 of 12.9 µM. However, it did not inhibit PG. The potent antifungal and antitumor activities of the protein suggest that it can be developed into an antifungal agent for combating M. arachidicola invasion in crops and an agent for cancer therapy in humans.

The pathogenesis-related protein PR-4b from Theobroma cacao presents RNase activity, Ca(2+) and Mg(2+) dependent-DNase activity and antifungal action on Moniliophthora perniciosa

BACKGROUND

The production and accumulation of pathogenesis-related proteins (PR proteins) in plants in response to biotic or abiotic stresses is well known and is considered as a crucial mechanism for plant defense. A pathogenesis-related protein 4 cDNA was identified from a cacao-Moniliophthora perniciosa interaction cDNA library and named TcPR-4b.

RESULTS

TcPR-4b presents a Barwin domain with six conserved cysteine residues, but lacks the chitin-binding site. Molecular modeling of TcPR-4b confirmed the importance of the cysteine residues to maintain the protein structure, and of several conserved amino acids for the catalytic activity. In the cacao genome, TcPR-4b belonged to a small multigene family organized mainly on chromosome 5. TcPR-4b RT-qPCR analysis in resistant and susceptible cacao plants infected by M. perniciosa showed an increase of expression at 48 hours after infection (hai) in both cacao genotypes. After the initial stage (24-72 hai), the TcPR-4b expression was observed at all times in the resistant genotypes, while in the susceptible one the expression was concentrated at the final stages of infection (45-90 days after infection). The recombinant TcPR-4b protein showed RNase, and bivalent ions dependent-DNase activity, but no chitinase activity. Moreover, TcPR-4b presented antifungal action against M. perniciosa, and the reduction of M. perniciosa survival was related to ROS production in fungal hyphae.

CONCLUSION

To our knowledge, this is the first report of a PR-4 showing simultaneously RNase, DNase and antifungal properties, but no chitinase activity. Moreover, we showed that the antifungal activity of TcPR-4b is directly related to RNase function. In cacao, TcPR-4b nuclease activities may be related to the establishment and maintenance of resistance, and to the PCD mechanism, in resistant and susceptible cacao genotypes, respectively.

Overexpression of the synthetic chimeric native-T-phylloplanin-GFP genes optimized for monocot and dicot plants renders enhanced resistance to blue mold disease in tobacco (N. tabacum L.)

To enhance the natural plant resistance and to evaluate the antimicrobial properties of phylloplanin against blue mold, we have expressed a synthetic chimeric native-phylloplanin-GFP protein fusion in transgenic Nicotiana tabacum cv. KY14, a cultivar that is highly susceptible to infection by Peronospora tabacina. The coding sequence of the tobacco phylloplanin gene along with its native signal peptide was fused with GFP at the carboxy terminus. The synthetic chimeric gene (native-phylloplanin-GFP) was placed between the modified Mirabilis mosaic virus full-length transcript promoter with duplicated enhancer domains and the terminator sequence from the rbcSE9 gene. The chimeric gene, expressed in transgenic tobacco, was stably inherited in successive plant generations as shown by molecular characterization, GFP quantification, and confocal fluorescent microscopy. Transgenic plants were morphologically similar to wild-type plants and showed no deleterious effects due to transgene expression. Blue mold-sensitivity assays of tobacco lines were performed by applying P. tabacina sporangia to the upper leaf surface. Transgenic lines expressing the fused synthetic native-phyllopanin-GFP gene in the leaf apoplast showed resistance to infection. Our results demonstrate that in vivo expression of a synthetic fused native-phylloplanin-GFP gene in plants can potentially achieve natural protection against microbial plant pathogens, including P. tabacina in tobacco.

Isolation and in-silico characterization of Peroxidase isoenzymes from Wheat (Triticum aestivum) against Karnal Bunt (Tilletia indica)

To investigate the role of Peroxidase and its physiological significance under Karnal Bunt (KB) were determined in resistant (HD-29) and susceptible genotype (WH-542) of wheat during different developmental stages. The enzymes were expressed constitutively in both the susceptible and resistant genotype. In gel assay and differential expression analysis of POD was significantly higher (p >0.05) in Sv and S2, than the S1 and S3 stages. in silico analysis of Peroxidase for eg. physico-chemical properties, secondary structural features and phylogenetic classification for comparative analysis. Motif and Domain analysis of Peroxidase by MEME, to be important for the biological functions, and studies of evolution. Our results clearly indicate that the enhanced expression of POD at the WS2 stage, which reinforces its role in stage dependent immunity against Karnal bunt and role of POD metabolism provides genotype and stage dependant structural barrier resistance in wheat against KB.

Purification and characterization of a novel anti-HSV-2 protein with antiproliferative and peroxidase activities from Stellaria media

A novel antiviral protein, designated as Stellarmedin A, was purified from Stellaria media (L.) Vill. (Caryophyllaceae) by using ammonium sulfate precipitation, cation-exchange chromatography system. Gel electrophoresis analysis showed that Stellarmedin A is a highly basic glycoprotein with a molecular weight of 35.1 kDa and an isoelectric point of ∼8.7. The N-terminal 14-amino acid sequence, MGNTGVLTGERNDR, is similar to those of other plant peroxidases. This protein inhibited herpes simplex virus type 2 (HSV-2) replication in vitro with an IC50 of 13.18 µg/ml and a therapeutic index exceeding 75.9. It was demonstrated that Stellarmedin A affects the initial stage of HSV-2 infection and is able to inhibit the proliferation of promyelocytic leukemia HL-60 and colon carcinoma LoVo cells with an IC50 of 9.09 and 12.32 µM, respectively. Moreover, Stellarmedin A has a peroxidase activity of 36.6 µmol/min/mg protein, when guaiacol was used as substrate. To our knowledge, this is the first report about an anti-HSV-2 protein with antiproliferative and peroxidase activities from S. media.

A lectin with highly potent inhibitory activity toward breast cancer cells from edible tubers of Dioscorea opposita cv. nagaimo

A 70-kDa galactose-specific lectin was purified from the tubers of Dioscorea opposita cv. nagaimo. The purification involved three chromatographic steps: anion exchange chromatography on a Q-Sepharose column, FPLC-anion exchange chromatography on a Mono Q column, and FPLC-gel filtration on a Superdex 75 column. The purified nagaimo lectin presented as a single 35-kDa band in reducing SDS-PAGE while it exhibited a 70-kDa single band in non-reducing SDS-PAGE suggesting its dimeric nature. Nagaimo lectin displayed moderate thermostability, retaining full hemagglutinating activity after heating up to 62°C for 30 minutes. It also manifested stability over a wide pH range from pH 2 to 13. Nagaimo lectin was a galactose-specific lectin, as evidenced by binding with galactose and galactose-containing sugars such as lactose and raffinose. The minimum concentration of galactose, lactose and raffinose required to exert an inhibitory effect on hemagglutinating activity of nagaimo lectin was 20 mM, 5 mM and 40 mM, respectively. Nagaimo lectin inhibited the growth of some cancer cell lines including breast cancer MCF7 cells, hepatoma HepG2 cells and nasopharyngeal carcinoma CNE2 cells, with IC(50) values of 3.71 µM, 7.12 µM and 19.79 µM, respectively, after 24 hour treatment with nagaimo lectin. The induction of phosphatidylserine externalization and mitochondrial depolarization indicated that nagaimo lectin evoked apoptosis in MCF7 cells. However, the anti-proliferative activity of nagaimo lectin was not blocked by application of galactose, signifying that the activity was not related to the carbohydrate binding specificity of the lectin.

Protein from red cabbage (Brassica oleracea) seeds with antifungal, antibacterial, and anticancer activities

A 30 kDa antifungal protein was purified from red cabbage ( Brassica oleracea ) seeds. It exhibited a molecular mass and N-terminal amino acid sequence disinct from those of previously isolated Brassica antifungal proteins. The protocol used entailed ion exchange chromatography on Q-Sepharose and SP-Sepharose followed by fast protein liquid chromatography on Mono S. The protein hindered mycelial growth in Mycosphaerella arachidicola (with an IC50=5 μM), Setospaeria turcica, and Bipolaris maydis. It also inhibited the yeast Candida albicans with an IC50=96 μM. It exerted its antifungal action by permeabilizing the fungal membrane as evidenced by staining with Sytox green. The antifungal activity was stable from pH 3 to 11 and from 0 to 65 °C. It manifested antibacterial activity against Pseudomonas aeruginosa (IC50=53 μM). Furthermore, after 48 h of culture, it suppressed proliferation of nasopharyngeal cancer and hepatoma cells with IC50=50 and 90 μM, respectively.

Structural-functional features of plant isoperoxidases

Current data on structural--functional features of plant peroxidases and their involvement in functioning of the pro-/antioxidant system responding to stress factors, especially those of biotic origin, are analyzed. The collection of specific features of individual isoforms allows a plant to withstand an aggressive influence of the environment. Expression of some genes encoding different isoperoxidases is regulated by pathogens (and their metabolites), elicitors, and hormone-like compounds; specific features of this regulation are considered in detail. It is suggested that isoperoxidases interacting with polysaccharides are responsible for a directed deposition of lignin on the cell walls, and this lignin in turn is concurrently an efficient strengthening material and protects the plants against pathogens.

An antifungal defensin from Phaseolus vulgaris cv. 'Cloud Bean'

An antifungal peptide with a defensin-like sequence and exhibiting a molecular mass of 7.3kDa was purified from dried seeds of Phaseolus vulgaris 'Cloud Bean'. The isolation procedure entailed anion exchange chromatography on DEAE-cellulose, affinity chromatography an Affi-gel blue gel, cation exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. Although the antifungal peptide was unadsorbed on DEAE-cellulose, it was adsorbed on both Affi-gel blue gel and SP-Sepharose. The antifungal peptide exerted antifungal activity against Mycosphaerella arachidicola with an IC(50) value of 1.8 μM. It was also active against Fusarium oxysporum with an IC(50) value of 2.2 μM. It had no inhibitory effect on HIV-1 reverse transcriptase when tested up to 100 μM. Proliferation of L1210 mouse leukemia cells and MBL2 lymphoma cells was inhibited by the antifungal peptide with an IC(50) of 10 μM and 40 μM, respectively.

Hemagglutinating activity of proteins from Parkia speciosa seeds

Proteins from Parkia speciosa Hassk. (Fabaceae) seeds were extracted and stepwise precipitated using ammonium sulfate. Proteins precipitated with 25% ammonium sulfate were separated by affinity chromatography on Affi-Gel Blue gel followed by protein liquid chromatography on Superdex 200. The protein Gj, which was identified as a protein similar to putative aristolochene synthase, 3'-partial from Oryza sativa L. (Poaceae), had hemagglutinating activity of 0.39 mug/muL. Moreover, fraction C2 from the proteins precipitated with 60% ammonium sulfate, separated by lectin-specific adsorption chromatography using Con A Sepharose, had hemagglutinating activity of 1.17 mug/muL. Using gel electrophoresis, two proteins C2a and C2b were separated, having molecular weights of 45 kDa and 23 kDa, respectively. From protein identification, C2a was found to be similar to the hypothetical protein B1342F01.11 from Oryza sativa, and C2b was similar to the hypothetical protein At1g51560 from Arabidopsis thaliana (L.) Heynh. (Brassicaceae).

A peptide with potent antifungal and antiproliferative activities from Nepalese large red beans

An antifungal defensin-like peptide with a molecular mass of 7.1kDa was isolated from dried Nepalese large red beans (Phaseolus angularis). The purification protocol employed included ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and SP-Sepharose. The antifungal peptide inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola with an IC(50) value of 1.4 and 1.8 microM, respectively. It did not inhibit HIV-1 reverse transcriptase when tested up to 200 microM. It exerted an antiproliferative action on L1210 leukemia cells and MBL2 lymphoma cells with an IC(50) of 15 and 60 microM, respectively.

Purification and characterization of a novel antifungal protein from Bacillus subtilis strain B29

An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatography on Bio-Gel P-100. The protein was absorbed on DEAE-cellulose and Bio-Gel P-100. The purified antifungal fraction was designated as B29I, with a molecular mass of 42.3 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), pI value 5.69 by isoelectric focusing (IEF)-PAGE, and 97.81% purity by high performance liquid chromatography (HPLC). B29I exhibited inhibitory activity on mycelial growth in Fusarium oxysporum, Rhizoctonia solani, Fusarium moniliforme, and Sclerotinia sclerotiorum. The 50% inhibitory concentrations (IC(50)) of its antifungal activity toward Fusarium oxysporum and Rhizoctonia solani were 45 and 112 micromol/L, respectively. B29I also demonstrated an inhibitory effect on conidial spore germination of Fusarium oxysporum and suppression of germ-tube elongation, and induced distortion, tumescence, and rupture of a portion of the germinated spores.

Isolation and biochemical characterization of a novel leguminous defense peptide with antifungal and antiproliferative potency

Leguminous plants have formed a popular subject of research owing to the abundance of proteins and peptides with important biological activities that they produce. The antifungal proteins and peptides have been purified from a number of leguminous species. However, research continues to discover novel antifungal plant-produced peptides and proteins are being needed, specially those novel ones with both antifungal activity and other significant bioactivities. The objective of this study was to isolate a novel peptide from Phaseolus limensis. A 6.8 kDa peptide designated Limyin, with both antifungal and antiproliferative activity, was isolated from the large lima bean (P. limensis) legumes. The isolation procedure consisted of extraction, precipitation, affinity chromatography on Affi-gel blue gel, ion chromatography on SP-Toyopearl, and gel filtration on Superdex 75. Its N-terminal sequence was determined to be KTCENLATYYRGPCF, showing high homology to defensin and defensin precursors from plants. It potently suppressed mycelial growth in Alternaria alternata, Fusarium solani, and Botrytis cinerea. Its antifungal activity was stable up to 80 degrees C. It showed antiproliferative activity towards tumor cells including human liver hepatoma cells Bel-7402 and neuroblastoma cells SHSY5Y. However, it had no effect on bacteria Staphylococcus aureus and Salmonella. The present findings make a significant addition of the research on leguminous plants.

Concurrent purification of two defense proteins from French bean seeds: a defensin-like antifungal peptide and a hemagglutinin

A purification protocol is described herein for concurrent isolation of two defense proteins including a 6‐kDa defensin‐like antifungal peptide and a 60‐kDa dimeric hemagglutinin from seeds of the French bean (Phaseolus vulgaris). It involved ion‐exchange chromatography on SP‐Sepharose, affinity chromatography on Affi‐gel blue gel, ion‐exchange chromatography on Q‐Sepharose, and gel filtration on Superdex Peptide (for defensin‐like antifungal peptide) or Superdex 200 (for hemagglutinin). Both antifungal and hemagglutinating activities were adsorbed on SP‐Sepharose and then on Affi‐gel blue gel. Hemagglutinin was subsequently unadsorbed and defensin‐like antifungal peptide adsorbed on Q‐Sepharose. The antifungal activity of the antifungal peptide was stable in the temperature range of 0–90 °C for 20 min, in the pH range of 4–10, and after exposure to trypsin (1 mg/ml) at 37 °C for 1 h. The hemagglutinin was stable from 10 to 80 °C, from pH 1 to 12, and after treatment with trypsin at 37 °C for 2 h. It inhibited [methyl‐³H]thymidine incorporation into breast cancer (MCF‐7), leukemia (L1210), hepatoma (HepG2) and human embryonic liver (WRL68) cells with an IC₅₀ of 6.6, 7, 13 and 15 µm, respectively, and elicited maximal mitogenic response from mouse splenocytes at 1 µm concentration. It curtailed HIV‐1 reverse transcriptase activity with an IC₅₀ of 1.9 µm, but was devoid of antifungal activity. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.

Hypotin, a novel antipathogenic and antiproliferative protein from peanuts with a sequence similar to those of chitinase precursors

A protein designated Hypotin, with both antifungal and antibacterial activity, was isolated from peanut (Arachis hypogaea) seeds. The isolation procedure included extraction, ammonium sulfate precipitation, affinity chromatography on Affi-gel blue gel, ion chromatography, and gel filtration. The protein exhibited a molecular mass of 30.4 kDa in SDS-polyacrylamide gel electrophoresis under both reducing and nonreducing conditions, indicating that it is a monomeric protein. Its N-terminal sequence was highly homologous to those of chitinases and chitinase precursors from plants. It exerted potent antifungal action toward a variety of fungal species, including Pythium aphanidermatum, Fusarium solani, Physalospora piricola, Alternaria alternata, Botrytis cinerea, and Fusarium oxysporum. In addition, this novel protein exhibited antiproliferative activity against tumor cells. These findings further the progress in the research of leguminous plants.

A relatively stable antifungal peptide from buckwheat seeds with antiproliferative activity toward cancer cells

An antifungal peptide with a molecular mass of approximately 4 kDa was isolated from buckwheat seeds by using ion-exchange chromatography on SP-Sepharose and Q-Sepharose, and gel filtration on Superdex peptide. The peptide was adsorbed on SP-Sepharose in 10 mM NH(4)OAc buffer (pH 4.5) and on Q-Sepharose in 10 mM NH(4)HCO(3) buffer (pH 9.4), and appeared to be highly purified after these two steps. It inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola with an IC(50) of 35 and 40 microM, respectively. Its antifungal activity was stable between 0 and 70 degrees C, and between pH 1.0/2.0 and 13. It inhibited proliferation of Hep G2 (hepatoma) cells, L1210 (leukemia) cells, breast cancer (MCF-7) cells, and liver embryonic WRL 68 cells with an IC(50) of 33, 4, 25, and 37 microM, respectively. On the other hand, the peptide was unable to evoke a mitogenic response from splenocytes or induce nitric oxide production by macrophages. It inhibited HIV-1 reverse transcriptase with an IC(50) of 5.5 microM.

The role of plant defence proteins in fungal pathogenesis

SUMMARY It is becoming increasingly evident that a plant-pathogen interaction may be compared to an open warfare, whose major weapons are proteins synthesized by both organisms. These weapons were gradually developed in what must have been a multimillion-year evolutionary game of ping-pong. The outcome of each battle results in the establishment of resistance or pathogenesis. The plethora of resistance mechanisms exhibited by plants may be grouped into constitutive and inducible, and range from morphological to structural and chemical defences. Most of these mechanisms are defensive, exhibiting a passive role, but some are highly active against pathogens, using as major targets the fungal cell wall, the plasma membrane or intracellular targets. A considerable overlap exists between pathogenesis-related (PR) proteins and antifungal proteins. However, many of the now considered 17 families of PR proteins do not present any known role as antipathogen activity, whereas among the 13 classes of antifungal proteins, most are not PR proteins. Discovery of novel antifungal proteins and peptides continues at a rapid pace. In their long coevolution with plants, phytopathogens have evolved ways to avoid or circumvent the plant defence weaponry. These include protection of fungal structures from plant defence reactions, inhibition of elicitor-induced plant defence responses and suppression of plant defences. A detailed understanding of the molecular events that take place during a plant-pathogen interaction is an essential goal for disease control in the future.

A thaumatin-like antifungal protein from the emperor banana

A 20-kDa protein with substantial N-terminal sequence homology to thaumatin-like proteins was isolated from ripe fruits of the emperor banana, Musa basjoo cv. 'emperor banana'. The isolation procedure entailed (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, and affinity chromatography on Affi-gel blue gel. The thaumatin-like protein inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola. However, it did not affect the mitogenic response of murine splenocytes or [methyl-(3)H] thymidine incorporation by tumor cells. The activity of HIV-1 reverse transcriptase was slightly inhibited.

An antifungal peptide from red lentil seeds

An antifungal peptide, with a molecular mass of 11 kDa, was isolated from dry seeds of the red lentil (Lens culinaris) using a procedure that involved four chromatographic steps. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and S-Sepharose. The final chromatographic step involved gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide inhibited mycelial growth in Mycosphaerella arachidicola with an IC50 of 36 microM. It also exhibited antifungal activity against Fusarium oxysporum, but there was no inhibitory activity toward tumor cell lines and human immunodeficiency virus type 1 reverse transcriptase (RT).

Isolation and characterization of a novel mung bean protease inhibitor with antipathogenic and anti-proliferative activities

A novel protease inhibitor, designated mungoin, with both antifungal and antibacterial activities, and exhibiting a molecular mass of 10kDa in SDS-polyacrylamide gel electrophoresis, was isolated from mung bean (Phaseolus mungo) seeds. The isolation procedure involved a combination of extraction, ammonium sulfate precipitation, ion exchange chromatography on CM-Sephadex, and high-performance liquid chromatography (HPLC) on SP-Toyopearl. Its isoelectric point was estimated to be 9.8 by isoelectric focusing. Its N-terminal amino acid sequence was determined to be EMPGKPACLDTDDFCYKP, demonstrating some resemblance to the C-terminal sequences of other protease inhibitors and inhibitor precursors from leguminous plants. It exerted a potent inhibitory action toward a variety of fungal species including Physalospora piricola, Mycosphaerella arachidicola, Botrytis cinerea, Pythium aphanidermatum, Sclerotium rolfsii and Fusarium oxysporum, as well as an antibacterial action against Staphylococcus aureus. In addition, this novel plant protease inhibitor displayed anti-proliferative activity toward tumor cells.

Induction of an anionic peroxidase in cowpea leaves by exogenous salicylic acid

Two isoperoxidases were detected in cowpea (Vigna unguiculata) leaves. Treatment of the primary leaves with 10mM salicylic acid increased the total peroxidase activity contributed by the anionic isoform. To isolate both the anionic and cationic peroxidases the leaf crude extract was loaded on a Superose 12 HR 10/30 column followed by chromatography on Mono-Q HR 5/5. Both enzymes were stable in a pH range from 5 to 7. The optimum-temperatures for the cationic and anionic peroxidase isoforms were, respectively, 20-30 degrees C and 30 degrees C. The dependence of guaiacol oxidation rate varying its concentration at constant H(2)O(2) concentration showed, for both enzymes, Michaelis-Menten-type kinetic. Apparent K(m)(s) were 0.8 and 4.8 microM for the cationic and anionic isoperoxidases, respectively.

A hemagglutinin with mitogenic activity from dark red kidney beans

A 67-kDa hemagglutinin composed of two identical subunits was purified from Phaseolus vulgaris cv. 'Dark Red Kidney Bean'. It was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel. The hemagglutinin was highly purified after the two aforementioned chromatographic steps as revealed by a single peak in gel filtration on Superdex 75 and a single band in SDS-PAGE. The hemagglutinating activity was stable between 25 degrees C and 70 degrees C, and between pH 4 and pH 11, and in the presence of a variety of divalent metal chlorides at 500 mM concentration. The activity was reduced by 50% at 80 degrees C, and also when the pH was lowered to 3 or elevated to 12. The activity was reduced by 75% in the presence of 250 mM KCl or NaCl. A variety of sugars tested failed to inhibit the hemagglutinating activity of the hemagglutinin. Although the hemagglutinin exhibited mitogenic activity toward murine splenocytes, it had no effect on the activity of HIV-1 reverse transcriptase or mycelial growth in the fungi Botrytis cinerea, Fusarium oxysporum and Mycosphaerella arachidicola. It exerted an antiproliferative activity on leukemia L1210 cells.

An antifungal protein from the pea Pisum sativum var. arvense Poir

An antifungal protein with a molecular mass of 11 kDa and a lysine-rich N-terminal sequence was isolated from the seeds of the pea Pisum sativum var. arvense Poir. The antifungal protein was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. It exerted antifungal activity against Physalospora piricola with an IC50 of 0.62 microM, and also antifungal activity against Fusarium oxysporum and Mycosphaerella arachidicola. It inhibited human immunodeficiency virus type 1 reverse transcriptase with an IC50 of 4.7 microM.

Horseradish peroxidase degrades lipid hydroperoxides and suppresses lipid peroxidation of polyunsaturated fatty acids in the presence of phenolic antioxidants

Linoleic acid hydroperoxide (LAOOH) was effectively degraded by horseradish peroxidase (HRP) in the presence of quercetin. Several natural phenolic antioxidants, such as quercetin, capsaicin, and alpha-tocopherol, acted as good hydrogen donors in the peroxidase reaction that occurs during lipid hydroperoxide degradation. However, glutathione, which is a non-phenolic antioxidant that acts as a hydrogen donor for glutathione peroxidase, could not suppress lipid peroxidation in the presence of HRP. Lipid hydroperoxides generated from eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also degraded with HRP in the presence of quercetin, and oxidative decomposition of DHA was suppressed by this reaction.

Limenin, a defensin-like peptide with multiple exploitable activities from shelf beans

From the seeds of the shelf bean, an antifungal peptide with a molecular mass of 6.5 kDa was isolated. The isolation procedure comprised affinity chromatography on Affi-gel blue gel, ion exchange chromatography on Mono S, and gel filtration on Superdex 75. The peptide was adsorbed on Affi-gel blue gel and Mono S. It potently suppressed mycelial growth in Botrytis cinerea, Fusarium oxysporum, and Mycosphaerella arachidicola with an IC(50) of 2.9, 2.1, and 0.34 microM, respectively. It exerted antibacterial activity toward several bacterial species with an IC(50) approximating 100 microM. [Methyl-(3)H]-thymidine incorporation into isolated mouse splenocytes was stimulated. [Methyl-(3)H]-thymidine incorporation into M1 (myeloma) and L1210 (leukemia) cells was inhibited. The peptide reduced the activity of HIV-1 reverse transcriptase and also inhibited translation in a cell-free rabbit reticulocyte lysate system.

An antifungal protein from flageolet beans

A protein with antifungal and hemagglutinating activities was isolated from dried flageolet beans (Phaseolus vulgaris cv. 'Flageolet Bean'). The protein was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. The protein demonstrated antifungal activity against Mycophaerella arachidicola with an IC50 of 9.8 microM, but was inactive toward Fusarium oxysporum and Botrytis cinerea. Its hemagglutinating activity could not be inhibited by a variety of the sugars tested. The activity was stable up to 60 degrees C. At 70 degrees C, 75% of the hemagglutinating activity remained while no activity was discernible at and above 100 degrees C. The hemagglutinating activity was stable in the presence of a variety of monovalent, divalent and trivalent chlorides, and also when the ambient pH changed from 3 to 12. It did not exert any mitogenic activity on mouse splenocytes in vitro. Neither did it inhibit HIV-1 reverse transcriptase. It inhibited [3H-methyl]-thymidine incorporation into leukemia L1210 cells with an IC50 of about 4 microM.

An antifungal peptide from the coconut

A chromatographic procedure consisting of ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and gel filtration by fast performance liquid chromatography on Supedex 75 was utilized to isolate a 10 kDa antifungal peptide from coconut flesh. The peptide was unadsorbed on DEAE-cellulose, but adsorbed on Affi-gel blue gel and CM-cellulose. It displayed antifungal activity against Fusarium oxysporum, Mycosphaerella arachidicola and Physalospora piricola. The IC50 values of its inhibitory activities on mycelial growth in M. arachidicola and HIV-1 reverse transcriptase activity were respectively 1.2 and 52.5 microM.

Lunatusin, a trypsin-stable antimicrobial peptide from lima beans (Phaseolus lunatus L.)

An anti-fungal peptide designated as lunatusin, with a molecular mass around 7kDa, was purified from the seeds of Chinese lima bean (Phaseolus lunatus L.). The peptide was isolated using a simple protocol consisting of affinity chromatography on Affi-gel blue gel and gel filtration on Superdex 75. Lunatusin exerted an anti-fungal activity toward fungal species such as Fusarium oxysporum, Mycosphaerella arachidicola and Botrytis cinerea, and an antibacterial action on, Bacillus megaterium, Bacillus subtilis, Proteus vulgaris and Mycobacterium phlei. It also inhibited proliferation in the breast cancer cell line MCF-7. Lunatusin reduced the activity of HIV-1 reverse transcriptase and it also inhibited translation in a cell-free rabbit reticulocyte lysate system. Its anti-fungal activity was retained after incubation with trypsin. Lunatusin elicited a mitogenic response from mouse splenocytes.

Pleurostrin, an antifungal peptide from the oyster mushroom

A 7kDa peptide, with inhibitory activity on mycelial growth in the fungi Fusaerium oxysporum, Mycosphaerella arachidicola and Physalospora piricola, was isolated from fresh fruiting bodies of the oyster mushroom. The isolation procedure entailed extraction with an aqueous buffer, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel and gel filtration by fast protein liquid chromatography on Superdex 75. The protein was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel. It demonstrated an N-terminal sequence different from known antifungal proteins and peptides.

Evaluation of lactoperoxidase system treatment to reduce anthracnose, stem-end rot, and bacterial black spot development during storage of mangoes

The lactoperoxidase system (LPS) was evaluated for the prevention of postharvest diseases caused by Xanthomonas campestris, Botryodiplodia theobromae, and Colletotrichum gloeosporioides in 'Keitt' and 'Kent' mangoes. The LPS treatment significantly reduced the disease development on both cultivars after storage at 12 degrees C for 2 weeks, which was followed by a ripening at 25 degrees C. The LPS treatment did not alter the sensory quality of mango fruits (color, firmness, titrable acidity, and total soluble solids) when compared to untreated fruits. The LPS thus presents good potential alternative to the chemical fungicides traditionally used to improve the shelf life of mangoes.

Phaseococcin, an antifungal protein with antiproliferative and anti-HIV-1 reverse transcriptase activities from small scarlet runner beans

From the seeds of small scarlet runner beans (Phaseolus coccineus 'Minor'), an antifungal protein with an N-terminal sequence homologous to those of defensins was isolated. The antifungal protein bound to Affi-gel blue gel and Mono S but it did not bind to DEAE-cellulose. It was further purified by gel filtration on a Superdex peptide column. It exhibited a molecular mass of 5422 Da as determined by mass spectrometry. The protein, designated as phaseococcin, suppressed mycelial growth in a number of fungi including Botrytis cinerea, Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, Physalospora piricola, and Rhizoctonia solani. It also inhibited proliferation in several Bacillus species and the leukemia cell lines HL60 and L1210 and curtailed the activity of HIV-1 reverse transcriptase. It did not affect proliferation of mouse splenocytes and neither did it inhibit protein synthesis in a cell-free rabbit reticulocyte lysate system.Key words: antifungal proteins, runner beans, antiproliferative.

Isolation of trichogin, an antifungal protein from fresh fruiting bodies of the edible mushroom Tricholoma giganteum

An antifungal protein was isolated from the mushroom Tricholoma giganteum var. golden blessings. The protocol included ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal protein, designated trichogin, was unadsorbed on DEAE-cellulose but was adsorbed on Affi-gel blue gel and CM-cellulose. It exhibited antifungal activity against Fusarium oxysporum, Mycosphaerella arachidicola and Physalospora piricola. Trichogin inhibited HIV-1 reverse transcriptase with an IC50 of 83 nM.

Vulgarinin, a broad-spectrum antifungal peptide from haricot beans (Phaseolus vulgaris)

From the seeds of haricot beans (Phaseolus vulgaris), an antifungal peptide with a molecular mass around 7 kDa was purified by using a simple protocol consisting of affinity chromatography on Affi-gel blue gel and gel filtration on Superdex 75. This peptide named vulgarinin manifested an antifungal activity toward fungal species such as Fusarium oxysporum, Mycosphaerella arachidicola, Physalospora piricola and Botrytis cinerea, and an antibacterial action on Mycobacterium phlei, Bacillus megaterium, Bacillus subtilis and Proteus vulgaris. It also inhibited proliferation in leukemia cell lines L1210 and M1 and breast cancer cell line MCF-7. This peptide could reduce the activity of HIV-1 reverse transcriptase and inhibited translation in a cell-free rabbit reticulocyte lysate system. Its antifungal activity was retained after incubation with trypsin.

Agrocybin, an antifungal peptide from the edible mushroom Agrocybe cylindracea

An antifungal peptide with a molecular mass of 9 kDa was isolated from fresh fruiting bodies of the mushroom Agrocybe cylindracea. The isolation procedure comprised ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono S, and FPLC-gel filtration on a Superdex 75 column. The antifungal peptide, designated as agrocybin, was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and Mono S. Agrocybin exerted antifungal activity against several fungal species but lacked inhibitory activity against bacteria when tested up to 300 microM. The activity of HIV-1 reverse transcriptase was attenuated in the presence of agrocybin. It exhibited weaker mitogenic activity than Con A on isolated murine splenocytes, but was devoid of antiproliferative activity on Hep G2 (hepatoma) cells when tested at 110 microM.

Isolation of alliumin, a novel protein with antimicrobial and antiproliferative activities from multiple-cloved garlic bulbs

A protein designated alliumin, with a molecular mass of 13 kDa and an N-terminal sequence similar to a partial sequence of glucanase, and demonstrating antifungal activity against Mycosphaerella arachidicola, but not against Fusarium oxysporum, was isolated from multiple-cloved garlic (Allium sativum) bulbs. The protein, designated as alliumin, was purified using ion exchange chromatography on DEAE-cellulose, CM-cellulose and Mono S, affinity chromatography on Affi-gel blue gel, and gel filtration on Superdex 75. Alliumin was unadsorbed on DEAE-cellulose, but was adsorbed on Affi-gel blue gel, CM-cellulose and Mono S. Its antifungal activity was retained after boiling for 1 h and also after treatment with trypsin or chymotrypsin (1:1, w/w) for 30 min at room temperature. Alliumin was inhibitory to the bacterium Pseudomonas fluorescens and exerted antiproliferative activity toward leukemia L1210 cells. However, it was devoid of ribonuclease activity, protease activity, mitogenic activity toward mouse splenocytes, and antiproliferative activity toward hepatoma Hep G2 cells.