• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.173-173
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• 2022

In this study, we investigated whether there is another amaranth GBSS isoform in an attempt to characterize the synthesis of amylose in the pericarp. We used I2/KI staining to analyze the temporal and spatial starch accumulation patterns during seed development. The spatiotemporal starch accumulation patterns in developing seeds were observed by staining with I2/KI. Starch granules were observed in the pericarp in the initial developmental stage (3 DAP). A few starch granules were detected in the perisperm in the early-late developmental stage (8 DAP), during which the pericarp starch contents rapidly decreased. Starch granules were distributed throughout the perisperm in the mid-late developmental stage (15 DAP). Similar results were reported for other cereal crops, including barley, rice, and sorghum. Starch granules in the pericarp are synthesized during the early seed developmental stages but are absent in mature seeds. We recently reported that starch deposits in the perisperm of developing amaranth seeds are detectable only after the initial developmental stage. Prior to this stage, the pericarp is the major site of starch deposition. A recent study suggested that GBSSII isoforms are responsible for amylose synthesis in pericarps.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.267-274
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• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.231-235
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• 2018

In this study, we demonstrate the conversion of starch to (R,R)-2,3-butanediol (2,3-BD) in a hybrid cell-free synthesis system containing a mixture of lysates derived from Escherichia coli (E. coli) and cyanobacteria. A sufficient pool of pyruvate required for the synthesis of 2,3-BD was generated by combining metabolic pathways of cyanobacteria and E. coli. Successful synthesis of 2,3-BD was achieved by additional modifications of the hybrid cell-free system with the enzymes required to convert pyruvate to 2,3-BD. The results demonstrate a new approach to harness biological pathways to expand the scope of cell-free metabolic engineering by cross-species combinations of cell lysates.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.514-520
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• 1991

Direct synthesis of cyclodextrin (CD) from extruded insoluble corn starch without liquefaction procedure using cyclodextrin glucanotransferase (CGTase) was carried out. Increased CD production rate and yield were achieved in heterogeneous enzyme reaction system containing extruded corn starch compared with those of conventional system employing liquefied or partially cyclized starch. At extruded starch concentration of 100 g/l the CD concentration and conversion yield were reached up to 54 g/l and 0.54, respectively. High purity of $\alpha \beta \gamma$-CDs without accumulation of undesirable malto-oligosaccharides was produced, furthermore, the residual extruded starch was easily separated by centrifugation from reaction mixture, whlch will facilitate the purification procedure. Granular structure of extruded starch was observed by SEM to investigate enzyme reaction mechanism. Supplemental addition of $\alpha$-amylase enhanced slightly the initial CD production rate, but it decomposed produced CD at the late stage. Various! extruded raw starches, such as, corn, rice, and barley were also suitable substrates for CD production.

• Korean Journal of Pharmacognosy
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• v.17 no.2
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• pp.134-138
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• 1986

Based on a tracer study, starch phosphorylase was implicated as an agent in the starch synthesis in sweet potato roots. The enzyme was purified from the tissue as a cluster of isozymes with an average mw of 205K (fresh roots) or 159K (roots stored for 3 mon.). On SDS polyacrylamide gel electrophoresis, one large subunit of 98K mw and several small ones of 47${\sim}57K mw were observed. From the mw data and the results of peptide mapping and immunoelectrophoretic blotting using mono- and polyclonal antibodies, it was deduced that a large part of the large subunit was cleaved at the middle part of the peptide chain to give rise to the small subunits, and on storage, the enzyme molecules were further modified by proteolysis. During the course of phosphorylase purification, a proteinaceous inhibitor of the enzyme was isolated. It had a mw of 250K and was composed of 5 identical subunits of 51K mw. In the direction of starch synthesis, the inhibitor showed a noncompetitive kinetics with a Ki of $1.3{\times}10^{-6}\;M$. By immunohistochemical methods, both the enzyme and the inhibitor were located on the cell wall and amyloplast. Crossreacting materials of the inhibitor were present in spinach leaf, potato tuber and rice grain. These findings indicate the wide occurrence of the inhibitor and also imply its possible participation in regulating starch phosphorylase activity in vivo.

• Elastomers and Composites
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• v.45 no.4
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• pp.272-279
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• 2010

Starch is an environmental-friendly natural source, more interests are attracted to use starch for synthesis of composites and coating sols. Starch-acrylic coating sols for architectural materials were synthesized by emulsion polymerization. The structures of synthesized materials were characterized by using Infrared spectra, $^1H$-NMR spectra, and physical characteristics were investigated by X-ray diffraction, foaming test, whiteness test, gloss test and tensile strength test. XRD results showed that starch in starch-acrylic copolymer matrix was in an amorphous state. Starch-acrylic emulsion was compounded with 1%, 3%, 5% foaming agent (n-pentane) and 60% $CaCO_3$ solution. The results showed that starch and foaming agent could increase the foamability. Tensile strength increased with the enhancement of starch and foaming agent concentration. But whiteness and gloss decreased with increase of starch and foaming agent concentration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.124-133
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• 2017

This experiment was conducted to evaluate the effects of high temperature on the stem, leaf and grain of barley during the ripening period and to provide information for the development of high-temperature cultivation techniques and adaptive varieties. We used an artificial climate control facility, to provide a temperature $3^{\circ}C$ higher than the normal average temperature during the ripening stage. Although the maximum rate of starch synthesis was increased at high temperature by approximately 11%, the starch content was decreased, because the period of starch synthesis ended 4 days earlier. As in the case of starch synthesis, the expression of genes related to starch synthesis was increased at the early ripening stage in the high temperature treatment, however, the duration of expression tended to decrease rapidly. Furthermore, the partitioning rate of assimilation products in the panicle increased to a greater extent in the high temperature treatment than in the control. In contrast, for the stem and leaf, the partitioning rate of assimilation products decreased more rapidly in the high temperature treatment than in the control. On the basis of these results, it can be considered that the translocation rate of assimilation products increased to a greater extent in the high temperature treatment than in the control at the early ripening stage. These results indicate that the decrease in grain weight at high temperature during the ripening stage is attributable to an increase in the speed of starch synthesis at high temperature, but the increase in ripening speed does not compensate for the shortening of the ripening period. Finally to develop varieties and cultivation techniques suited to high temperature, we need to focus on physiological characteristics related to the duration of starch synthesis.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.67-68
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• 2003

Native corn starch and montmorillonite caly nanocomposites were prepared using the glycerol as the plasticizer. These were characterized by mechanical analysis, X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The tensile strength increased with the clay content to a maximum point and then decreased due to gapping between the two phases. Dispersion of the layered silicate within the starch was verified using X-ray diffraction pattern. Examination of these materials by scanning electron showed that intercalates have good wetting to the starch surface.

• Polymer(Korea)
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• v.34 no.1
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• pp.58-62
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• 2010

The acrylic monomers were graft-polymerized to starch as matrix polymer by emulsion polymerization. Viscosity and particle size of the emulsion were increased with starch contents due to interaction with water and particle swelling toward the water phase by hydroxy group of starch. Chemical stability of the emulsion was also increased with enhancement of starch, but water and alkali resistance were reduced with increasing starch contents because of the increasement of hyrophilicity. Opacity of the starch-acrylic emulsion compound containing calcium carbonate was decreased with contents of starch by its intrinsic color. The film of starch-acrylic polymer showed more clear appearance with increasing starch contents owing to enhancement of amorphous state.

• Proceedings of the Korean Fiber Society Conference
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• 1995.10a
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• pp.99-100
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• 1995