Many chitinases and their genes have been obtained from various plants. To understand structural features of plant chitinases, some classification systems have been proposed by some research groups. However, the complicated multiple classification of plant chitinases frequently confuses researchers. In this article, structures and classification systems of plant chitinases are reviewed, and their issues are discussed. Plant chitinase is considered to protect plants against fungal pathogens by degrading chitin, a major component of the cell walls of many fungi. The antifungal activity of various chitinases derived from various plant sources has been investigated, but a correlation between the structure and the antifungal activity of the proteins has been unclear. To exhibit antifungal activity, a chitinase must bind to fungal cell walls, and then, it should degrade the chitin in them. Roles of the chitin-binding domain and catalytic domain in antifungal activity of plant chitinases are discussed.
It is believed that human milk oligosaccharides (HMO) act as receptor analogues that inhibit the attachment of pathogenic microorganisms to the infant colon, but the direct involvement of HMO in anti infection has not as yet been demonstrated. The present study was conducted to clarify whether HMOs as well as commercially available galacto oligosaccharides (GO), from which lactose has been removed, affect the expression of toll-like receptor (TLR) 2 and 4, and of MD2 mRNA in the HT-29, human colonic cell line. HT-29 cells were treated with neutral human milk oligosaccharides (nHMOs), which had been separated from the acidic oligosaccharide fraction and also from lactose, as well as with GOs. HT-29 cells were treated with specific oligosaccharides of major components of nHMO or GO. The mRNA expression of TLR2, 4 and MD2 were measured using Real-time RT-PCR normalized to glyceraldehydes 3-phosphate dehydrogenase (GAPDH) mRNA expression. The addition of nHMO affected the expression of TLR2. Treatment with 1.0 mg/mL of nHMO as well as with 0.5 mg and 1.0 mg/mL GO enhanced the mRNA expression of TLR4. In experiments with specific oligosaccharides, treatments with 3'-sialyllactose (3'-SL), 6'-sialyllactose (6'-SL) or 6'-galactosyllactose (6'-GL) increased the expression of TLR-2, while the administration of lacto-N-fucopentaose I (LNFP I), 3'-, 6'-SL or 6'-GL enhanced that of TLR4. These results suggest that HMOs as well as GOs had a direct effect on colonic epithelial cells, with induction of the mRNA expression of TLR.
Enset (Ensete ventricosum, Family Musaceae) is a plant distributed in Eastern and Southern Africa, often called “false banana” for its close resemblance to the banana plant (Musa acuminate, Family Musaceae). The plant is only cultivated in Southern and Southwestern Ethiopia as a staple. Enset accumulates starch in the pseudostem and underground corm. Though enset starch is utilized in foods and for industrial purposes such as textile and paper sizing, pharmaceuticals, very limited research has been done on the properties of the extracted starch. The useful properties of enset starch were characterized by comparison with starches of potato, sago and corn and shown in a starch diagram, where the analytical results including granule size, X-ray diffraction pattern, amylose content, gelatinization behavior, stability and various rheological properties of gel are presented in comparison with those of reference starches. The characteristics of gelatinization behaviors, quick gel formation, gel stability during cold storage, and high firmness and stickiness of enset starch gel described in this paper would be useful for various foods, for example, in Blanc-mange and Japanese sweet “Kudzu mochi” for body formation, and in various sauces and soups as a thickener due to stable starch viscosity and high gel stickiness during storage. The gel whiteness of enset starch is appropriate for milk or soybean curd containing processed foods, where pure white color is appreciated. Properties of enset starch gel will be widely useful as a body forming agent and thickener of various foods in home cooking and food industries.
Coenzyme Q10 (CoQ10) is a well-known antioxidant agent that has low solubility in water and poor absorption in humans. CoQ10-cyclodextrin (CD) complex powders containing 20-24% (w/w) CoQ10 were prepared to investigate the effects of different CDs on three properties of CoQ10: aqueous solubility, heat of fusion, and absorption in humans. The aqueous solubility of CoQ10 was increased by α-CD and dextrin, while β-CD, γ-CD and β-Iso® formed an insoluble complex with CoQ10. β-CD, γ-CD and β-Iso® improved the thermal property of CoQ10, as determined by differential scanning calorimetry. That is, β-CD, γ-CD and β-Iso® most likely formed complexes with CoQ10, as the CoQ10 endothermic peak obtained by differential scanning calorimetry greatly decreased in the presence of these compounds. For the absorption studies, 20 healthy female volunteers were divided randomly into four groups and orally administered either CoQ10, the CoQ10-β-CD complex, CoQ10-γ-CD complex or CoQ10-β-Iso® complex containing 0.30 g CoQ10 under fasting conditions. The concentration of CoQ10 in plasma before and 2, 4, 6, 8 and 24 h after sample administration was measured by HPLC analysis, and the plasma concentration of exogenous CoQ10 was calculated as the plasma concentration of CoQ10 before administration subtracted from the value after administration. The area under the plasma exogenous CoQ10 concentration/time-course curve from 0 to 8 h of the three complex groups was significantly higher than that of the CoQ10 group, indicating that β-CD, γ-CD and β-Iso® accelerate the absorption of CoQ10 in humans.
Stevia rebaudiana Morita, which produces a higher ratio of rebaudioside A relative to stevioside, was developed as a cultivar by selective breeding of S. rebaudiana Bertoni. The structures of 21 compounds (termed SG1-20) extracted from the leaves with hot water were characterized by ESI-MS/MS, 1H- and 13C-NMR and/or chemical analyses after separation by HPLC on an Amide-80 column. Among them, ten compounds (about 7% of the total) were found to be new steviol glycosides that contained the following sugar chains linked at C13 (R2) and C19 (R1) of the aglycon steviol. SG4: R1 = H-, R2 = Rhaα1-2(Glcβ1-3)Glcβ1-; SG7: R1 = Glcβ1-, R2 = Glcβ1-3Glcβ1-; SG12: R1 = Glcβ1-3Glcβ1-, R2 = Glcβ1-2(Glcβ1-3)Glcβ1-; SG14: R1 = Glcβ1-, R2 = Glcβ1-3Rhaα1-2(Glcβ1-3)Glcβ1-; SG15: R1 = Glcβ1-, R2 = Glcβ1-6Glcβ1-2(Glcβ1-3)Glcβ1-; SG16-I: R1 = Glcβ1-2Glcβ1-, R2 = Rhaα1-2(Glcβ1-3)Glcβ1-; SG16-II: R1 = Rhaα1-2Glcβ1-, R2 = Glcβ1-2(Glcβ1-3)Glcβ1-; SG17: R1 =, R2 = Glcβ1-2(Glcβ1-3)Glcβ1-; SG19: R1 = Rhaα1-2(Glcβ1-3)Glcβ1-, R2 = Glcβ1-2(Glcβ1-3)Glcβ1-; SG20: R1 = Glcβ1-3Rhaα1-2(Glcβ1-3)Glcβ1-, R2 = Glcβ1-2(Glcβ1-3)Glcβ-. Eleven compounds were previously known steviol glycosides, among which rebaudioside A (61.6% of total), stevioside (9.2%) and rebaudioside C (7.5%) were predominant.
In this study, it was investigated the properties of Stein-Hall (SH) type and No Carrier (NC) type corrugating adhesives made from corn starch. SH type adhesive is composed from carrier and main starch portions. It had been reported that NC type adhesive was composed from partially swelled homogeneous starch granule suspension. The distribution of starch granule diameter in both types adhesives and simple slurry respectively containing 21.6% corn starch were a little different. In NC type, slightly swelled granule of 29-101 μm diameter increased by 16% compared with the simple slurry. And in SH type, the distribution had two peaks. The first primary peak was similar to the simple slurry and the secondary peak of 10.5% distribution was broad range of 44-101 μm in diameter. However, the gelatinization enthalpy of NC type was not significantly different from SH type during 0.54-0.94% caustic soda concentration, and in both types, they were decreased to 70% as the concentration of caustic soda increased from 0 to 0.94%. These gelatinization complete temperature (Tc) became a little higher in NC type compared with SH type. In various NC type adhesives of containing 14.4-34.4% starch and SH type of 19.2-24.7%, the ratio of Ford cup (FC) viscosity to Brookfield (B.) viscosity of NC type was half as large as SH type at 40°C. Thus, the viscous properties were different in two types. NC type adhesive was seemed to be high fluidity and good application at glue roll as a result of its low FC viscosity and high B. viscosity. In common practical viscosity (540-2500 m Pa·s at 40°C) of various NC type adhesives containing 14.4-34.4% starch, the proportion of soluble starch to the whole starch increased to 19.0 from 1.2% and the swelling ratio (the ratio of swelled starch volume for air dried starch volume) increased to 5.40 from 2.10 with decreasing starch concentration to 14.4 from 34.4%, and conversely the density of their granule decreased to 1.10 from 1.24 g/cm3. In the NC type adhesives with various viscosities at 40°C of 21.6 and 28.7% starch concentration, the proportion of soluble starch increased as its viscosity became higher, but the swelling ratio of starch granule was almost the same. As the result, the viscosity of NC type adhesives was depended on the proportion of soluble starch rather than the swelling ratio. So, it was thought that the viscosity at preparing the NC type was adjusted with the proportion of soluble starch but not with the swelling ratio, according to the treatment time with high concentration (0.79-1.30%) of caustic soda. As the result from the starch granule diameter distribution, the NC type was not homogeneous and contained the partially swelled starch granules as a part. In the several concentration of caustic soda, the gelatinization enthalpies of NC type adhesives were almost same but not small compared with the SH type contrary to the expectation. It was seemed that SH type and NC type adhesives were characterized as similar endothermic gelatinization properties.
Sucrose isomerases from Protaminobacter rubrum, SmuA, and from Pseudomonas mesoacidophila MX-45, MutB, have been crystallized, and their three-dimensional structures solved. Determination of these crystal structures in their native states as well as in complex with substrate and substrate analogues have contributed to the visualization of a part of the double displacement reaction mechanism of this class of enzymes, and to the understanding of the specificity of the products. Comparative structural studies between the three-dimensional structures of trehalulose synthase, MutB, and the isomaltulose synthase, SmuA, have been conducted as well.