Abundant class III acidic chitinase homologue in tamarind (Tamarindus indica) seed serves as the major storage protein

IgE-Mediated Legume Allergy: A Pediatric Perspective

Legumes are an inexpensive and essential protein source worldwide. The most consumed legumes include peanuts, soybeans, lentils, lupines, peas, common bean and chickpeas. In addition, the food industry is growing interested in expanding the use of legumes to partially replace or substitute cereals. Legumes were described to cause IgE-mediated allergies, and their growing use may also increase the incidence of allergy. The epidemiology of legume allergy varies by region; peanuts and soybeans are the legumes most involved in food allergies in Western countries, whereas lentils, peas, and chickpeas are reported as culprit allergens mainly in the Mediterranean area and India. This review, edited by the Italian Society of Pediatric Allergology and Immunology, summarizes the scientific literature on legume allergy in children and proposes a diagnostic workup and therapeutic approach.

The anti-Alzheimer potential of Tamarindus indica: an in vivo investigation supported by in vitro and in silico approaches

Tamarindus indica Linn. (Tamarind, F. Fabaceae) is one of the most widely consumed fruits in the world. A crude extract and different fractions of T. indica (using n-hexane, dichloromethane, ethyl acetate, and n-butanol) were evaluated in vitro with respect to their DPPH scavenging and AchE inhibition activities. The results showed that the dichloromethane and ethyl acetate fractions showed the highest antioxidant activities, with 84.78 and 86.96% DPPH scavenging at 0.10 μg mL-1. The n-hexane, dichloromethane, and ethyl acetate fractions inhibited AchE activity in a dose-dependent manner, and the n-hexane fraction showed the highest inhibition at 20 μg mL-1. The results were confirmed by using n-hexane, dichloromethane, and ethyl acetate fractions in vivo to regress the neurodegenerative features of Alzheimer's dementia in an aluminum-intoxicated rat model. Phytochemical investigations of those three fractions afforded two new diphenyl ether derivative compounds 1-2, along with five known ones (3-7). The structures of the isolated compounds were confirmed via 1D and 2D NMR and HRESIMS analyses. The isolated compounds were subjected to extensive in silico-based investigations to putatively highlight the most probable compounds responsible for the anti-Alzheimer activity of T. indica. Inverse docking studies followed by molecular dynamics simulation (MDS) and binding free energy (ΔG) investigations suggested that both compounds 1 and 2 could be promising AchE inhibitors. The results presented in this study may provide potential dietary supplements for the management of Alzheimer's disease.

Biotechnological Eminence of Chitinases: A Focus on Thermophilic Enzyme Sources, Production Strategies and Prominent Applications

BACKGROUND

Chitin, the second most abundant polysaccharide in nature, is a constantly valuable and renewable raw material after cellulose. Due to advancement in technology, industrial interest has grown to take advantage of the chitin.

OBJECTIVE

Now, biomass is being treated with diverse microbial enzymes or cells for the production of desired products under best industrial conditions. Glycosidic bonds in chitin structure are degraded by chitinase enzymes, which are characterized into number of glycoside hydrolase (GHs) families.

METHODS

Thermophilic microorganisms are remarkable sources of industrially important thermostable enzymes, having ability to survive harsh industrial processing conditions. Thermostable chitinases have an edge over mesophilic chitinases as they can hydrolyse the substrate at relatively high temperatures and exhibit decreased viscosity, significantly reduced contamination risk, thermal and chemical stability and increased solubility. Various methods are employed to purify the enzyme and increase its yield by optimizing various parameters such as temperature, pH, agitation, and by investigating the effect of different chemicals and metal ions etc. Results: Thermostable chitinase enzymes show high specific activity at elevated temperature which distinguish them from mesophiles. Genetic engineering can be used for further improvement of natural chitinases, and unlimited potential for the production of thermophilic chitinases has been highlighted due to advancement in synthetic biological techniques. Thermostable chitinases are then used in different fields such as bioremediation, medicine, agriculture and pharmaceuticals.

CONCLUSION

This review will provide information about chitinases, biotechnological potential of thermostable enzyme and the methods by which they are being produced and optimized for several industrial applications. Some of the applications of thermostable chitinases have also been briefly described.

Chitinase family genes in grape differentially expressed in a manner specific to fruit species in response to Botrytis cinerea

Chitinases (Chi), an important resistance-related protein, act against fungal pathogens by catalyzing the fungal cell wall, whereas are involved in different biological pathways in grape. In this study, we found 42 Chi family genes in Vitis vinifera L. (VvChis) and evaluated their expression levels after Botrytis infection, stress hormones like ethylene (ETH) and methyl-jasmonate (MeJA), and abiotic stresses like salinity and temperature changes in ripened fruits. VvChis were categorized into five groups including A, B, C, D, and E belonged to glycoside hydrolase family 18 and 19 (GH18 and GH19) according to genes structure, which expression analysis showed distinct temporal and spatial expression patterns changed in different tissues and various development stages. Different responsive elements to biotic and abiotic stresses were determined in the promoter regions of VvChis, specially elicitor-responsive element that was conserved among all VvChis genes. The expression levels of VvChis in groups A, B, and E increased after Botrytis cinerea infection in leaves and berries. Meanwhile, VvChis in glycoside hydrolase family 18 (GH18) were up-regulated under MeJA and ETH treatment, although the induction of VvChis by low temperature was more significant than high temperature. The expression of VvChis was also positively correlated with the concentration of NaCl treatment. Furthermore, differential gene-overexpression of VvChi5, VvChi17, VvChi22, VvChi26, and VvChi31 in strawberry and tomato fruits demonstrated the involvement of various isoforms in resistance to Botrytis infection through antioxidant system and lignin accumulation, which led to a reduction of damage. Among different isoforms of VvChis, we confirmed the interaction of Chi17 with Metallothionein (MTL) as oxidative stress protection, which suggests VvChis can modulate oxidative stress during postharvest storage in ripened fruits.

Identification and characterization of a novel chitinase with antifungal activity from 'Baozhu' pear (Pyrus ussuriensis Maxim.)

A novel chitinase from the 'Baozhu' pear was found, purified, and characterized in this report. This chitinase was a monomer with a molecular mass of 28.9 kDa. Results of the internal peptide sequence analyses classify this chitinase as a class III chitinase. In the enzymatic hydrolytic assay, this chitinase could hydrolyze chitin derivatives into di-N-acetylchitobiose (GlcNAc2) as a major product in the initial phase, as well as hydrolyze GlcNAc2 into N-acetylglucosamine (GlcNAc), which represents both chitobiosidase and β-N-acetylglucosaminase activity. Biological analyses showed that this chitinase exhibits strong antifungal activity toward agricultural pathogenic fungi. In total, chitinase from 'Baozhu' pear is a novel bifunctional chitinase that could be a potential fungicide in the biological control of plant diseases.

Bio-potency of a 21 kDa Kunitz-type trypsin inhibitor from Tamarindus indica seeds on the developmental physiology of H. armigera

A trypsin inhibitor purified from the seeds of Tamarindus indica by Sephadex G-75, DEAE-Sepharose and Trypsin-Sepharose CL-4B columns was studied for its antifeedant, larvicidal, pupicidal and growth inhibitory activities against Helicoverpa armigera larvae. Tamarindus trypsin inhibitor (TTI) exhibited inhibitory activity towards total gut proteolytic enzymes of H. armigera (~87%) and bovine trypsin (~84%). Lethal doses which caused mortality and weight reduction by 50% were 1% w/w and 0.50% w/w, respectively. IC50 of TTI against Helicoverpa midgut proteases and bovine trypsin were ~2.10 µg/ml and 1.68 µg/ml respectively. In larval feeding studies the 21 kDa Kunitz-type protein was found to retard growth and development, prolonged the larval-pupal development durations along with adversely affecting the fertility and fecundity of H. armigera. In artificial diet at 0.5% w/w TTI, the efficiency of conversion of ingested food as well as of digested food, relative growth rate, growth index declined whereas approximate digestibility, metabolic cost, relative consumption rate, consumption index and total developmental period enhanced for H. armigera larvae. These results suggest that TTI has toxic and adverse effect on the developmental physiology of H. armigera and could be useful in controlling the pest H. armigera.

Proteomic identification of gravitropic response genes in peanut gynophores

Peanut (Arachis hypogaea L.) is one of the most important oil-bearing crops in the world. The gravitropic response of peanut gynophores plays an essential role in peanut reproductive development. In this study, we developed an in vitro culture system and applied it to the study of peanut gynophore gravitropism. By comparing the proteomes of gynophores grown in vitro with the tip pointing upward (gravity stimulation sample) and downward (natural growth control) at 6h and 12h, we observed 42 and 39 with significantly altered expression pattern at 6 and 12h, respectively. Out of these proteins, 13 proteins showed same expression profiling at both 6h and 12h. They were identified by MALDI-TOF/TOF and further characterized with quantitative real time RT-PCR. Among the 13 identified proteins, two were identified as class III acidic endochitinases, two were identified as Kunitz trypsin protease inhibitors, and the remaining proteins were identified as pathogenesis-related class 10 protein, Ara h 8 allergen isoform 3, voltage-dependent anion channel, gamma carbonic anhydrase 1, germin-like protein subfamily 3 member 3 precursor, chloride channel, glycine-rich RNA-binding protein and gibberellin receptor GID1. Real time RT-PCR analysis revealed that transcriptional regulation is consistent with expression at the protein level for class III acidic endochitinase, Kunitz trypsin protease inhibitor, chloride channel and pathogenesis-related class 10 protein, while the expression of the other 7 proteins might be regulated at post-transcriptional levels. This study identified several potential gravitropic response proteins in peanut gynophores and helps to understand early gravitropic responses in peanut gynophores.

BIOLOGICAL SIGNIFICANCE

The gravitropic response of the peanut gynophores plays an essential role in peanut production. However, the molecular mechanism responsible for gravitropic responses in the peanut gynophores has not been explored yet. The result generated in this study may provide in vitro culture system for gravitropism study of plant gravitropic response and novel insights into the proteome-level response and give a more comprehensive understanding of early gravitropic response in peanut gynophores. This article is part of a Special Issue entitled: Translational Plant Proteomics.

Structural investigation of a novel N-acetyl glucosamine binding chi-lectin which reveals evolutionary relationship with class III chitinases

The glycosyl hydrolase 18 (GH18) family consists of active chitinases as well as chitinase like lectins/proteins (CLPs). The CLPs share significant sequence and structural similarities with active chitinases, however, do not display chitinase activity. Some of these proteins are reported to have specific functions and carbohydrate binding property. In the present study, we report a novel chitinase like lectin (TCLL) from Tamarindus indica. The crystal structures of native TCLL and its complex with N-acetyl glucosamine were determined. Similar to the other CLPs of the GH18 members, TCLL lacks chitinase activity due to mutations of key active site residues. Comparison of TCLL with chitinases and other chitin binding CLPs shows that TCLL has substitution of some chitin binding site residues and more open binding cleft due to major differences in the loop region. Interestingly, the biochemical studies suggest that TCLL is an N-acetyl glucosamine specific chi-lectin, which is further confirmed by the complex structure of TCLL with N-acetyl glucosamine complex. TCLL has two distinct N-acetyl glucosamine binding sites S1 and S2 that contain similar polar residues, although interaction pattern with N-acetyl glucosamine varies extensively among them. Moreover, TCLL structure depicts that how plants utilize existing structural scaffolds ingenuously to attain new functions. To date, this is the first structural investigation of a chi-lectin from plants that explore novel carbohydrate binding sites other than chitin binding groove observed in GH18 family members. Consequently, TCLL structure confers evidence for evolutionary link of lectins with chitinases.

Chitinase III in pomegranate seeds (Punica granatum Linn.): a high-capacity calcium-binding protein in amyloplasts

Chitinases are a class of ubiquitous proteins that are widely distributed in plants. Defense is the major natural role for chitinases, primarily against fungal pathogens. Little is known regarding their non-defensive roles in seeds. In this study, a new class III chitinase from pomegranate seeds (pomegranate seed chitinase, PSC) was isolated and purified to homogeneity. The native state of PSC is a monomer with a molecular weight of approximately 30 kDa. This chitinase naturally binds calcium ions with high capacity and low affinity, suggesting that PSC is a calcium storage protein. Consistent with this idea, its amino acid sequence (inferred from cDNA) is rich in acidic amino acid residues, especially Asp, similar to reported calcium storage proteins. The presence of calcium considerably improves the stability of the protein but has little effect on its enzymatic activity. Transmission electron microscopy analyses indicate that, similar to phytoferritin, this enzyme is widely distributed in the stroma of amyloplasts of the embryonic cells, suggesting that amyloplasts in seeds could serve as an alternative plastid for calcium storage. Indeed, the transmission electron microscopy results showed that, within the embryonic cells, calcium ions are mainly distributed in the stroma of the amyloplasts, consistent with a role for PSC in calcium storage. Thus, the plant appears to have evolved a new plastid for calcium storage in seeds. During seed germination, the content of this enzyme decreases with time, suggesting that it is involved in the germination process.

ICChI, a glycosylated chitinase from the latex of Ipomoea carnea

A multi-functional enzyme ICChI with chitinase/lysozyme/exochitinase activity from the latex of Ipomoea carnea subsp. fistulosa was purified to homogeneity using ammonium sulphate precipitation, hydrophobic interaction and size exclusion chromatography. The enzyme is glycosylated (14-15%), has a molecular mass of 34.94 kDa (MALDI-TOF) and an isoelectric point of pH 5.3. The enzyme is stable in pH range 5.0-9.0, 80 degrees C and the optimal activity is observed at pH 6.0 and 60 degrees C. Using p-nitrophenyl-N-acetyl-beta-D-glucosaminide, the kinetic parameters K(m), V(max), K(cat) and specificity constant of the enzyme were calculated as 0.5mM, 2.5 x 10(-8)mol min(-1)microg enzyme(-1), 29.0 s(-1) and 58.0mM(-1)s(-1) respectively. The extinction coefficient was estimated as 20.56 M(-1)cm(-1). The protein contains eight tryptophan, 20 tyrosine and six cysteine residues forming three disulfide bridges. The polyclonal antibodies raised and immunodiffusion suggests that the antigenic determinants of ICChI are unique. The first fifteen N-terminal residues G-E-I-A-I-Y-W-G-Q-N-G-G-E-G-S exhibited considerable similarity to other known chitinases. Owing to these unique properties the reported enzyme would find applications in agricultural, pharmaceutical, biomedical and biotechnological fields.

Purification, crystallization and preliminary crystallographic studies of a Kunitz-type proteinase inhibitor from tamarind (Tamarindus indica) seeds

A Kunitz-type proteinase inhibitor has been purified from tamarind (Tamarindus indica) seeds. SDS-PAGE analysis of a purified sample showed a homogeneous band corresponding to a molecular weight of 21 kDa. The protein was identified as a Kunitz-type proteinase inhibitor based on N-terminal amino-acid sequence analysis. It was crystallized by the vapour-diffusion method using PEG 6000. The crystals belonged to the orthorhombic space group C222(1), with unit-cell parameters a = 37.2, b = 77.1, c = 129.1 A. Diffraction data were collected to a resolution of 2.7 A. Preliminary crystallographic analysis indicated the presence of one proteinase inhibitor molecule in the asymmetric unit, with a solvent content of 44%.

Isolation, purification, crystallization and preliminary crystallographic studies of chitinase from tamarind (Tamarindus indica) seeds

A protein with chitinase activity has been isolated and purified from tamarind (Tamarindus indica) seeds. N-terminal amino-acid sequence analysis of this protein confirmed it to be an approximately 34 kDa endochitinase which belongs to the acidic class III chitinase family. The protein was crystallized by the vapour-diffusion method using PEG 4000. The crystals belonged to the tetragonal space group P4(1), with two molecules per asymmetric unit. Diffraction data were collected to a resolution of 2.6 A.