Purification and characterisation of a novel chitinase from persimmon (Diospyros kaki) with antifungal activity

A novel bi-functional cold-adaptive chitinase from Chitinilyticum aquatile CSC-1 for efficient synthesis of N-acetyl-D-glucosaminidase

In order to better utilize chitinolytic enzymes to produce high-value N-acetyl-D-glucosamine (GlcNAc) from chitinous waste, there is an urgent need to explore bi-functional chitinases with exceptional properties of temperature, pH and metal tolerance. In this study, we cloned and characterized a novel bi-functional cold-adaptive chitinase called CaChi18A from a newly isolated strain, Chitinilyticum aquatile CSC-1, in Bama longevity village of Guangxi Province, China. The activity of CaChi18A at 50 °C was 4.07 U/mg. However, it exhibited significant catalytic activity even at 5 °C. Its truncated variant CaChi18A_ΔChBDs, containing only catalytic domain, demonstrated significant activity levels, exceeding 40 %, over a temperature range of 5-60 °C and a pH range of 3 to 10. It was noteworthy that it displayed tolerance towards most metal ions at a final concentration of 0.1 mM, including Fe3+ and Cu2+ ions, retaining 122.52 ± 0.17 % and 116.42 ± 1.52 % activity, respectively. Additionally, it exhibited favorable tolerance towards organic solvents with the exception of formic acid. Interestedly, CaChi18A and CaChi18A_ΔChBDs had a low Km value towards colloidal chitin (CC), 0.94 mg mL-1 and 2.13 mg mL-1, respectively. Both enzymes exhibited chitobiosidase and N-acetyl-D-glucosaminidase activities, producing GlcNAc as the primary product when hydrolyzing CC. The high activities across a broader temperature and pH range, strong environmental adaptability, and hydrolytic properties of CaChi18A_ΔChBDs suggested that it could be a promising candidate for GlcNAc production.

Mechanisms of persimmon pectin methyl esterase activation by high pressure processing based on chemical experiments and molecular dynamics simulations

High pressure processing (HPP) was found to have a kinase effect on persimmon pectin methyl esterase (PME), while the mechanism remains unclear. In this study, chemical experiments and molecular dynamics (MD) simulations were used to reveal its mechanisms. Persimmon PME was first extracted and purified using ion exchange columns with 81.89% purity. After 500 MPa/5 min, PME activity increased 11.3%, the α-helix and β-folding decreased 10.8% and 6.1% compared to the 0.1 MPa group, respectively. MD results showed that HPP decreased the volume, increased the number of hydrogen bonds between PME and pectin. Under high pressure, Asp-157, Asp-136 and Gln-135 in the enzyme activity center remained stable, while the positions of Arg-225 and Gln-113 changed a lot. The conformation of the substrate binding channel also changed. The secondary structure and volume changes of the HPP-treated PME affected the active center and substrate channels, ultimately altering the activity.

The synergistic action of two chitinases from Vibrio harveyi on chitin degradation

In this study, two chitinases (VhChit2 and VhChit6) from Vibrio harveyi possessed specific activity of 36.5 and 20.8 U/mg, respectively. Structure analysis indicates that their amino acid composition of active sites is similar, but the substrate binding cleft of VhChit2 is deeper than that of VhChit6. They were shown to have a synergistic effect on chitin degradation, and the optimized degree of synergy and the degradation ratio of chitin reached 1.75 and 23.6 %, respectively. The saturated adsorption capacity of VhChit2 and VhChit6 adsorbed in 1 g of chitin was 48.5 and 33.4 mg. It was found that VhChit2 and VhChit6 had different adsorption sites on chitin, making more enzymes absorbed by chitin. Furthermore, the combined use of VhChit2 and VhChit6 increased their binding force of chitinases with the substrate. The synergistic action of VhChit2 and VhChit6 may be attributed to their different adsorption sites on chitin and the increased binding force with chitin.

The potential of plant proteins as antifungal agents for agricultural applications

Fungal pathogens induce a variety of diseases in both plants and post-harvest food crops, resulting in significant crop losses for the agricultural industry. Although the usage of chemical-based fungicides is the most common way to control these diseases, they damage the environment, have the potential to harm human and animal life, and may lead to resistant fungal strains. Accordingly, there is an urgent need for diverse and effective agricultural fungicides that are environmentally- and eco-friendly. Plants have evolved various mechanisms in their innate immune system to defend against fungal pathogens, including soluble proteins secreted from plants with antifungal activities. These proteins can inhibit fungal growth and infection through a variety of mechanisms while exhibiting diverse functionality in addition to antifungal activity. In this mini review, we summarize and discuss the potential of using plant antifungal proteins for future agricultural applications from the perspective of bioengineering and biotechnology.

Kinetic, Thermodynamic and Bio-applicable Studies on Aspergillus niger Mk981235 Chitinase

Chitinases have many applications in food, agricultural, medical, and pharmaceutical fields. This study succeeded in investigating Aspergillus niger MK981235 chitinase in the spot of its physiochemical, kinetic, thermodynamic, and application. The optimum temperature, pH and p-nitrophenyl-β-d-N-acetyl glucosaminide (PNP-β-GlcNAc) concentration to obtain the highest chitinase activity of 2334.79 U ml−1 were at 60 °C, 5 and 0.25%, respectively. The kinetic parameters, including Km and Vmax were determined to be 0.78 mg ml−1 and 2222.22 µmol ml−1 min−1, respectively. Furthermore, the thermodynamic parameters T1/2, D-values, ΔH, ΔG and ΔS at 40, 50 and 60 °C were determined to be (864.10, 349.45, 222.34 min), (2870.99, 1161.07, 738.74 min), (126.40, 126.36, 126.32 kJ mol−1), (101.59, 100.62, 100.86 kJ mol−1), (74.50, 76.17, 47.24 J mol−1 K−1), respectively. A. niger chitinase showed, insecticidal activity on Galleria mellonella by feeding and spraying treatments (72 and 52%, respectively), anti-lytic activity against Candida albicans, and effectiveness in improving the dye removal in the presence of crab shell powder as bio-absorbant. A. niger chitinase can be used in the pharmaceutical field for the bio-control of diseases caused by C. albicans and for the pretreatment of wastewater from the textile industry.

Graphical Abstract

Improvement in the in vitro Digestibility of Shrimp Meal by the Addition of Persimmon Peel

The present study was conducted to analyze the chemical properties of persimmon peel (PP) and the in vitro digestibility of shrimp meal (SM) diets containing PP. Discussions whether PP can be used as a feed additive to promote digestion of SM in chickens are also included. The chemical composition and chitinase activity of dried PP was studied. SM diets containing PP were formulated according to the 4 by 6 factorial design: 4 levels of SM (0%, 10%, 15%, and 20%) × 6 levels of PP (0%, 2%, 4%, 6%, 8%, and 10%). The in vitro digestibility of dry matter (IVDMD), crude protein (IVCPD), and chitin (IVCD) was also studied. PP was rich in nitrogen-free extract (NFE, about 74%) and tannin (2.8%), and the highest chitinase activity of PP was observed at pH 4.5. Approximately 50% of chitinase activity was also observed at acidic (3.0) and alkaline (8.0) pH. Its activity was slightly affected by pepsin treatment. IVDMD increased upon addition of up to 8% PP, but decreased with an increase in the level of SM. When PP level was increased up to 6%, IVCPD in the group containing 0% SM, changed slightly; however, an increasing trend was observed in the other groups. When PP level was more than 6%, IVCPD decreased in all the groups. IVCD increased dose-dependently with increasing level of PP and decreased with increasing level of SM. In conclusion, PP was rich in NFE, had high chitinase activity, and improved all digestibility parameters, such as IVDMD, IVCPD, and IVCD, in SM diets where the PP level was under 6%. Thus, up to 6% of PP can be safely included in SM diets as a digestion promoter.

Multiple strategies to improve the yield of chitinase a from Bacillus licheniformis in Pichia pastoris to obtain plant growth enhancer and GlcNAc

Chitinase and chitin-oligosaccaride can be used in multiple field, so it is important to develop a high-yield chitinase producing strain. Here, a recombinant Pichia pastoris with 4 copies of ChiA gene from Bacillus licheniformis and co-expression of molecular chaperon HAC1 was constructed. The amount of recombinant ChiA in the supernatant of high-cell-density fermentation reaches a maximum of 12.7 mg/mL, which is 24-fold higher than that reported in the previous study. The recombinant ChiA can hydrolyze 30% collodidal chitin with 74% conversion ratio, and GlcNAc is the most abundant hydrolysis product, followed by N, N′-diacetylchitobiose. Combined with BsNagZ, the hydrolysate of ChiA can be further transformed into GlcNAc with 88% conversion ratio. Additionally, the hydrolysate of ChiA can obviously accelerate the germination growth of rice and wheat, increasing the seedling height and root length by at least 1.6 folds within 10 days.

Characterization of a Novel Chitinase from Sweet Potato and Its Fungicidal Effect against Ceratocystis fimbriata

Black rot, caused by Ceratocystis fimbriata, is a destructive disease of sweet potatoes (Ipomoea batatas). In this study, a novel chitinase (IbChiA) was screened from sweet potatoes, which showed a remarkably higher expression level in resistant varieties than in susceptible ones after inoculation with C. fimbriata. Sequence analysis indicated that IbChiA belongs to family 19 class II extracellular chitinase with a MW of 26.3 kDa and pI of 5.96. Recombinant IbChiA, produced by Pichia pastoris, displayed antifungal activity and stability. IbChiA could restrain the mycelium extension of C. fimbriata. FDA/PI double staining combined with transmission electron microscopy observation revealed the remarkable fungicidal effect of IbChiA on the conidia of C. fimbriata. The disease symptoms on the surface of slices and tuberous roots of sweet potatoes were significantly reduced after treatment with IbChiA. These results indicated that IbChiA could be used as a potential biofungicide to replace chemical fungicides.

TIM barrel fold and glycan moieties in the structure of ICChI, a protein with chitinase and lysozyme activity

The ICChI is a 35-kDa, glycosylated protein isolated from the latex of the weed Ipomoea carnea. It displays chitinase and lysozyme activity, which could be important for the defense against pathogenic fungi, insects and bacteria. The ICChI enzyme was crystallized, and a diffraction data set was collected from a single crystal to 1.42 Å resolution. The crystals belong to the primitive tetragonal space group P4₃2₁2, with unit-cell parameters a = b = 57.9, c = 172.0 Å, and α = β = γ = 90°. The structure was elucidated by molecular replacement method using a mixed model of three homologous structures from the N-terminal sequence of ICChI. The refined model consists of 272 amino acid residues and has a R_factor of 18.93% and R_free of 22.42%. The protein consists of a single globular domain with a (α/β)₈ triosephosphate isomerase barrel fold. Three of the consensus sites for N-glycosylation viz., Asn⁴⁵, Asn¹⁷², and Asn¹⁹⁴ containing carbohydrate moieties N-Acetylglucosamine (NAG), mannose, fucose, and xylose. The putative catalytic residues are Asp¹²⁵, Glu¹²⁷, and Tyr¹⁸⁴. The crystal structure may provide fundamental information of GH18 family chitinases.

A biophysical and structural study of two chitinases from Agave tequilana and their potential role as defense proteins

Plant chitinases are enzymes that have several functions, including providing protection against pathogens. Agave tequilana is an economically important plant that is poorly studied. Here, we identified a chitinase from short reads of the A. tequilana transcriptome (AtChi1). A second chitinase, differing by only six residues from the first, was isolated from total RNA of plants infected with Fusarium oxysporum (AtChi2). Both enzymes were overexpressed in Escherichia coli and analysis of their sequences indicated that they belong to the class I glycoside hydrolase family19, whose members exhibit two domains: a carbohydrate-binding module and a catalytic domain, connected by a flexible linker. Activity assays and thermal shift experiments demonstrated that the recombinant Agave enzymes are highly thermostable acidic endochitinases with Tm values of 75 °C and 71 °C. Both exhibit a molecular mass close to 32 kDa, as determined by MALDI-TOF, and experimental pIs of 3.7 and 3.9. Coupling small-angle x-ray scattering information with homology modeling and docking simulations allowed us to structurally characterize both chitinases, which notably show different interactions in the binding groove. Even when the six different amino acids are all exposed to solvent in the loops located near the linker and opposite to the binding site, they confer distinct kinetic parameters against colloidal chitin and similar affinity for (GlnNAc)_6, as shown by isothermal titration calorimetry. Interestingly, binding is more enthalpy-driven for AtChi2. Whereas the physiological role of these chitinases remains unknown, we demonstrate that they exhibit important antifungal activity against chitin-rich fungi such as Aspergillus sp. DATABASE: SAXS structural data are available in the SASBDB database with accession numbers SASDDE7 and SASDDA6. ENZYMES: Chitinases (EC3.2.1.14).

Efficient enzymatic hydrolysis of ionic liquid pretreated chitin and its dissolution mechanism

Colloidal chitin, the substrate of chitinase with an open hydrated gel-like structure, can be obtained by treatment using either traditional hydrochloric acid (HCl) or ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]). IL-pretreated chitin provided an efficient production of N-acetylglucosamine (175.62 mg g chitin) and N,N'-diacetylchitobiose (341.70 mg g chitin) with a conversion of 61.49% at 48 h catalyzed by chitinase from Streptomyces albolongus ATCC 27414. A short time second homogenization treatment after IL pretreatment can increase the conversion to 76.11%. A comprehensive characterization and comparison of chitin with different pretreatments suggested that enzymatic performances were correlated with the structural changes (size of the grains and porosity), high decrease in crystallinity, and high enzyme adsorption. The NMR spectroscopy studies of N-acetylglucosamine solvation in [Emim][OAc] clearly suggest that hydrogen bonding is formed between the hydroxyls of N-acetylglucosamine and both the anions and cations of the IL.

Activation and conformational changes of chitinase induced by ultrasound

This study investigated the effect of ultrasound on chitinase activity and conformational changes. Results revealed that ultrasound activated chitinase with a maximum enhancement of 19.17% compared with the untreated chitinase. Furthermore, an increase of V_max and a decrease of K_m after sonication were obtained, illustrating that the affinity between chitinase and substrate was intensified. No obvious effect on the tolerance to most metal ions was exhibited whether sonicated or not (p > 0.05). The conformational changes of chitinase were analyzed by circular dichroism (CD), Fourier transform infrared (FTIR), Raman and fluorescence spectroscopy. Results indicated that the activation of chitinase induced by ultrasound was presumably due to the decrease of tryptophan on the chitinase surface and the increase of β-sheet and random coil in chitinase secondary conformation. In brief, ultrasound is a possible way to activate chitinase to increase its application in food industry.

A chitinase with antifungal activity from naked oat (Avena chinensis) seeds

A chitinase was purified from naked oat (Avena chinensis) seeds using simple chromatographic techniques. Its molecular weight and isoelectric point were determined as 35 kDa and 8.9, respectively. The purified chitinase exhibited specific activity of 3.6 U/mg and 15.6% yield using colloidal chitin as substrate. Partial amino acid sequence analysis and homology search indicated that it probably belonged to Class I plant chitinase, glycosyl hydrolase family 19. With chitin as substrate, the optimum pH and temperature of the chitinase were pH 7.0 and 40°C, respectively. The chitinase was remarkably stable from 30°C up to 50°C, but was inactivated at high temperatures above 85°C. Antifungal activity in vitro tests demonstrated this purified chitinase had potent, dose-dependent inhibitory activity against the fungi Panus conchatus and Trichoderma reesei. PRACTICAL APPLICATIONS: Chitinase has broad applications in many fields including the food industry and is recognized as one of the antifungal substances with potential use in plant disease resistance or biological control in agriculture. This study developed cost-effective purification methods for producing chitinase from naked oat (Avena chinensis) seeds, which may favor large-scale production of the enzyme. The remarkable stability of the chitinase at moderate temperatures (30°C-50°C), makes it a potentially useful enzyme in bioprocessing to produce chitooligosaccharides for various applications in the food, health, and agriculture sectors.

Cloning, characterization and substrate degradation mode of a novel chitinase from Streptomyces albolongus ATCC 27414

A novel chitinase gene was cloned from Streptomyces albolongus ATCC 27414, and expressed successfully in Escherichia coli BL21. The recombinant enzyme (SaChiA4) belongs to glycoside hydrolases (GH) family 18 and consists of a catalytic domain and a chitin binding domain (CBD) in its C-terminus. SaChiA4 was purified homogeneously (specific activity of 66.2 U/mg with colloidal chitin as substrate), and showed a molecular mass of approximately 47 kDa. SaChiA4 showed its optimal activity at pH 5.0 and 55 °C and exhibited remarkable pH and temperature stability. SaChiA4 has been proved to have a higher specificity toward glycosides containing acetyl groups and hydrolyzes the substrates in a non-processive manner with higher ability to produce (GlcNAc)₂ and GlcNAc. The results indicated that SaChiA4 is a novel endo-type chitinase, which has potential applications in the treatment of chitin wastes and the production of (GlcNAc)₂.

Purification, physicochemical and thermodynamic studies of antifungal chitinase with production of bioactive chitosan-oligosaccharide from newly isolated Aspergillus griseoaurantiacus KX010988

In our search for chitinase and chitosanase producer from unconventional sources, the marine-derived fungus Aspergillus griseoaurantiacus KX010988 was obviously the best producer of the highest chitinase and chitosanase activities by solid state fermentation of potato shells. Chitinase was purified in three steps involving ammonium sulphate precipitation, DEAE-cellulose ion-exchange chromatography and Sephacryl S-300 gel chromatography. 12.55 fold increase in purity with a recovery of 17.6 was obtained. The molecular mass of the purified chitinase was found to be 130kDa. It was optimally active at pH 4.5 and 40°C. K_m and V_max values were 0.22mgmL^-1 and 19.6μmolemin^-1mg^-1 respectively. Mn²⁺ and Zn²⁺ ions lead to increased chitinase activity. While Fe²⁺and Cu²⁺ions strongly inhibited the chitinase activity. The thermodynamics of pure chitinase including activation energy for thermal denaturation (E_a,d), change of free energy (ΔG_d), enthalpy(ΔH_d), entropy(ΔS_d) and half life values (T_1/2) at 40, 50 and 60°C were determined. Chitinase showed antifungal activity against pathogenic fungus Fusarium solani. Chitosanase was partially purified by acetone precipitation (50-75%) v/v concentration. The hydrolytic products of moderate molecular weight of chitosan by chitosanase were analyzed by thin layer chromatography (TLC) after 12 and 24h respectively. Chitosan-oligosaccharides showed good antibacterial and antioxidant activities.

Transglycosylation by a chitinase from Enterobacter cloacae subsp. cloacae generates longer chitin oligosaccharides

Humans have exploited natural resources for a variety of applications. Chitin and its derivative chitin oligosaccharides (CHOS) have potential biomedical and agricultural applications. Availability of CHOS with the desired length has been a major limitation in the optimum use of such natural resources. Here, we report a single domain hyper-transglycosylating chitinase, which generates longer CHOS, from Enterobacter cloacae subsp. cloacae 13047 (EcChi1). EcChi1 was optimally active at pH 5.0 and 40 °C with a K_m of 15.2 mg ml⁻¹, and k_cat/K_m of 0.011× 10² mg⁻¹ ml min⁻¹ on colloidal chitin. The profile of the hydrolytic products, major product being chitobiose, released from CHOS indicated that EcChi1 was an endo-acting enzyme. Transglycosylation (TG) by EcChi1 on trimeric to hexameric CHOS resulted in the formation of longer CHOS for a prolonged duration. EcChi1 showed both chitobiase and TG activities, in addition to hydrolytic activity. The TG by EcChi1 was dependent, to some extent, on the length of the CHOS substrate and concentration of the enzyme. Homology modeling and docking with CHOS suggested that EcChi1 has a deep substrate-binding groove lined with aromatic amino acids, which is a characteristic feature of a processive enzyme.

Biochemistry of fish stomach chitinase

Fish are reported to exhibit chitinase activity in the stomach. Analyses of fish stomach chitinases have shown that these enzymes have the physiological function of degrading chitinous substances ingested as diets. Osteichthyes, a group that includes most of the fishes, have several chitinases in their stomachs. From a phylogenetic analysis of the chitinases of vertebrates, these particular molecules were classified into a fish-specific group and have different substrate specificities, suggesting that they can degrade ingested chitinous substances efficiently. On the other hand, it has been suggested that coelacanth (Sarcopterygii) and shark (Chondrichthyes) have a single chitinase enzyme in their stomachs, which shows multiple functions. This review focuses on recent research on the biochemistry of fish stomach chitinases.

Cloning, Expression and 3D Structure Prediction of Chitinase from Chitinolyticbacter meiyuanensis SYBC-H1

Two CHI genes from Chitinolyticbactermeiyuanensis SYBC-H1 encoding chitinases were identified and their protein 3D structures were predicted. According to the amino acid sequence alignment, CHI1 gene encoding 166 aa had a structural domain similar to the GH18 type II chitinase, and CHI2 gene encoding 383 aa had the same catalytic domain as the glycoside hydrolase family 19 chitinase. In this study, CHI2 chitinase were expressed in Escherichia coli BL21 cells, and this protein was purified by ammonium sulfate precipitation, DEAE-cellulose, and Sephadex G-100 chromatography. Optimal activity of CHI2 chitinase occurred at a temperature of 40 °C and a pH of 6.5. The presence of metal ions Fe³⁺, Fe²⁺, and Zn²⁺ inhibited CHI2 chitinase activity, while Na⁺ and K⁺ promoted its activity. Furthermore, the presence of EGTA, EDTA, and β-mercaptoethanol significantly increased the stability of CHI2 chitinase. The CHI2 chitinase was active with p-NP-GlcNAc, with the K_m and V_m values of 23.0 µmol/L and 9.1 mM/min at a temperature of 37 °C, respectively. Additionally, the CHI2 chitinase was characterized as an N-acetyl glucosaminidase based on the hydrolysate from chitin. Overall, our results demonstrated CHI2 chitinase with remarkable biochemical properties is suitable for bioconversion of chitin waste.

Purification and characterization of a novel chitinase from Trichosanthes dioica seed with antifungal activity

Chitinases are a group of enzymes that show differences in their molecular structure, substrate specificity, and catalytic mechanism and widely found in organisms like bacteria, yeasts, fungi, arthropods actinomycetes, plants and humans. A novel chitinase enzyme (designated as TDSC) was purified from Trichosanthes dioica seed with a molecular mass of 39±1 kDa in the presence and absence of β-mercaptoethanol. The enzyme was a glycoprotein in nature containing 8% neutral sugar. The N-terminal sequence was determined to be EINGGGA which did not match with other proteins. Amino acid analysis performed by LC-MS revealed that the protein was rich in leucine. The enzyme was stable at a wide range of pH (5.0-11.0) and temperature (30-90 °C). Chitinase activity was little bit inhibited in the presence of chelating agent EDTA (ethylenediaminetetraaceticacid), urea and Ca(2+). A strong fluorescence quenching effect was found when dithiothreitol and sodium dodecyl sulfate were added to the enzyme. TDSC showed antifungal activity against Aspergillus niger and Trichoderma sp. as tested by MTT assay and disc diffusion method.

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.

Chitinase III in Euphorbia characias latex: Purification and characterization

This paper deals with the purification of a class III endochitinase from Euphorbia characias latex. Described purification method includes an effective novel separation step using magnetic chitin particles. Application of magnetic affinity adsorbent noticeably simplifies and shortens the purification procedure. This step and the subsequently DEAE-cellulose chromatography enable to obtain the chitinase in homogeneous form. One protein band is present on PAGE in non-denaturing conditions and SDS-PAGE profile reveals a unique protein band of 36.5 ± 2 kDa. The optimal chitinase activity is observed at 50 °C, pH 5.0. E. characias latex chitinase is able to hydrolyze colloidal chitin giving, as reaction products, N-acetyl-D-glucosamine, chitobiose and chitotriose. Moreover, we observed that calcium and magnesium ions enhance chitinase activity. Finally, we cloned the cDNA encoding the E. characias latex chitinase. The partial cDNA nucleotide sequence contains 762 bp, and the deduced amino acid sequence (254 amino acids) is homologous to the sequence of several plant class III endochitinases.

Differentiations of chitin content and surface morphologies of chitins extracted from male and female grasshopper species

In this study, we used Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), and scanning electron microscopy (SEM) to investigate chitin structure isolated from both sexes of four grasshopper species. FT-IR, EA, XRD, and TGA showed that the chitin was in the alpha form. With respect to gender, two main differences were observed. First, we observed that the quantity of chitin was greater in males than in females and the dry weight of chitin between species ranged from 4.71% to 11.84%. Second, using SEM, we observed that the male chitin surface structure contained 25-90 nm wide nanofibers and 90-250 nm nanopores, while no pores or nanofibers were observed in the chitin surface structure of the majority of females (nanofibers were observed only in M. desertus females). In contrast, the elemental analysis, thermal properties, and crystalline index values for chitin were similar in males and females. Also, we carried out enzymatic digestion of the isolated chitins using commercial chitinase from Streptomyces griseus. We observed that there were no big differences in digestion rate of the chitins from both sexes and commercial chitin. The digestion rates were for grasshoppers' chitins; 88.45-95.48% and for commercial chitin; 94.95%.