The major protein associated with starch granules from kidney bean (Phaseolus vulgaris L .) seeds is a granule-bound starch synthase I (designated PvGBSSI) with the molecular mass of 60 kDa. To analyze the nature of native granule-bound starch synthase I (GBSSI) enzyme, not the enzymes solubilized from starch granules, a study was undertaken to identify the GBSSI sequence expressed during seed development and to characterize the enzymatic properties of the coded recombinant enzyme . A cDNA clone (designated pvgbssl) was isolated from a cDNA library of kidney bean immature seeds . The predicted primary sequence of mature PvGBSSI displayed significant identity (66-81 %) to those of other GBSSI members . Analyses of Northern blot and starch granule proteins revealed that both transcript and protein for PvGBSSI showed maximum levels at the late to mature stages of seed maturation . To investigate enzymatic properties, recombinant PvGBSSI (rPvGBSSI) was purified from Escherichia coil as a single band of protein on SDS-polyacrylamide gel by one-step column chromatography. The activity of rPvGBSSI was stimulated 1.7-fold in the presence of 0.25 M citrate. The affinity for amylopectin with 0.25 M citrate was much higher than for that without citrate, while the maxim um velocities were constant with or without citrate .
The polysaccharide was isolated from Hizikia fusiformis (Hijiki), which was harvested in Okinawa Prefecture, Japan. The yield of the polysaccharide was 0 .4% (w/w) based on wet seaweed. The total carbohy drate, uronic acid, ash and sulfuric acid of the polysaccharide were 66.5, 13.7, 30.8 and 26.3%, respectively. After the acid hydrolysis of the polysaccharide, L-fucose, D-galactose, D-glucose, D-mannose, D-xylose and Dglucuronic acid were identified by liquid chromatography. The molar ratio of these sugar components and sulfuric acid was calculated to be L-Fuc : D-Gal : D-Glc : D-Man : D-Xyl : D-GIcA : H2SO4= 5 : 1 : 1 : 0.5 :0.5 : 2 : 7. The molecular mass of the polysaccharide was estimated by gel chromatography to be about 4.3×104. The IR spectrum of the polysaccharide was in agreement with that of standard fucoidan. The L-fucose, Dglucuronic acid and acetyl group were identified by 1H- and 13C-NMR spectroscopy . The 1H-NMR spectraldata suggests that Fucoidan is mainly composed of 3-linked unsulfated, 4-linked unsulfated, 3-linked 2-mono-O-sulfated, 4-linked 2-mono-O-sulfated and 3-linked 2, 4-di-O-sulfated L-fucopyranose.
The oxidative stabilization of α-amylase from Bacillus sp . strain KSM-1378 (AmyK) was achievedby replacing Met202 with non-oxidizable amino acid residues. Computer-aided modeling of the enzyme suggested that Met202 among a total of eleven Met residues was spatially the closest to, although 10-14 Å away from, the catalytic site. The recombinant mutant enzymes were purified from cultures of Bacillus subtilis cells harboring the respective mutated genes. The results indicated that 1) the wild -type enzyme was readily inactivated by incubation with H2O2; 2) the change from Met to non-oxidizable Thr, Len, Ile, Ser, or Ala at posi-ti on 202 conferred high oxidative stability against H2O2; and 3) the increases in the substrate affinity (1/Km) and catalytic efficiency (kcat/Km) for borohydride-reduced amylose occurred with enlargement of the position 202 side chain in the mutant enzymes. These results suggest that oxidation of Met202 to the sulfoxide deriva tive interfered with substrate binding, thereby abolishing the enzyme activity .
L-Ascorbic acid (AsA) was reacted at 55°C for 5-7 h with 5 eq of palmitic, stearic, oleic, linoleic, linolenic and conjugated linoleic acids in 2-methyl-2-butanol (tertiary amyl alcohol, TAA) under catalysis by immobilized lipase (Candida antarctica) to give 3755% of pure 6-esters of AsA. The esters were isolated in elemental-pure form without chromatography. The esterification reaction also proceeded in acetonitrile and dimethyl sulfoxide, but not in nitromethane nor dimethylformamide. Adding drying salts and waterconsuming reagents or adding a low level of water to reaction mixtures in TAA gave reduced yields of Lascorbyl 6-palmitate. When the 6-oleate ester was stirred with lipase and oleic acid in TAA under the conditions used in esterification, about 44% of the ester was found in equilibrium with 56% of free AsA. t-Amyl palmitate was synthesized chemically; that ester was not detected in the lipase-catalyzed esterification. Those data show that primary hydroxyls were acylated selectively by the lipase, and that yields were optimum when the water in a reaction mixture was controlled.
Nine kinds of glucan-producing strains were isolated in their culture supernatant from the lines of a sugar-manufacturing factory. Eight strains produced water-soluble glucan.13C NMR analysis suggested that five out of the nine glucans mainly consisted of 6-Glcp and the other four glucans were branched. Among the 6-Glcp glucan-producing strains, S-51 was selected because it had the highest extracellular glucansucrase activity. S-51 strain was identified as Leuconostoc sp. Only one kind of glucansucrase with a molecular mass of 165 kDa was found in the culture supernatant of strain S-51. Optimum temperature and pH of the S-51 glucansucrase were 35°C and 5.5, respectively. Compared with the B-512F glucansucrase, S-51 glucansucrase has a lower Km value and was slightly more stable at varying pHs and temperatures.
Sembei produced from normal rice is one type of Japanese traditional rice cracker (Beika) and generally produced by successive processes of milling washed rice with a smooth-rolling mill, of pasting steamed and kneaded rice-flour, of drying raw rice-paste in two steps, and of roasting the dried rice-paste. As many processes are dependent on sense of smell of a craftsman, planning the mechanization is not easy. Furthermore, a response to various tastes of consumers and a constant supply of Beika of high quality are also very important in business. So, objective data for understanding the complex process is desired in the manufacture of Japanese rice crackers. The degree of swelling after roasting rice-paste, which is analyzed by specific volume in the Beika industry and expressed as "Uki, " is thought to be related to the unique taste coupled with soft feeling. The specific volume of Sembei produced from rices cultivated in Hokkaido was larger than that of Sembei from rices cultivated in the main island of Japan. Chain distributions of outer-layer of amylopectin molecules were also investigated through HPAEC-PAD analyses of partially hydrolyzed starches with isoamy lase and it was found that chains of the outer-layer of the former amylopectin were shorter than those of the latter. From these results, it was suggested that the swelling was related to the molecular network formed through drying rice-paste and the network was concerned not only with amylose and protein but also with amylopectin, which is the main component of normal rice starch.
Through analysis the greatest amount of the indigestible fraction in commercially available starch hydrolyzates was found to be acid converted maltodextrins and glucose syrups. For dextrins, it was found that acid-converted dextrin contains a greater amount of indigestible fraction than dextrin treated with heat pan without using acids. The method to obtain the indigestible fraction on an industrial scale has investigated. The amount of increase in indigestible fraction contained in acid-converted dextrin depended on the reaction time. Further, the average molecular weight of the indigestible fractions increased in relation to the heating temperature. Finally, a production process to obtain indigestible fraction from acid converted dextrin at industrial scale was developed, through dextrinization, enzyme treatments, refining, fractionation and drying, using the existing production facilities. The indigestible fraction obtained was designated as indigestible dextrin.There was no significant difference in composition between indigestible dextrin produced from corn starchand that produced from potato starch.
The relationship between taste properties of cooked rice and gelatinization and retrogradation properties of rice was studied. Eight varieties of rice, differing in taste or amylose content, were examined for thermal properties as starch by Differential Scanning Calorimetry (DSC), pasting and gel properties as flour by Rapid Visco Analyser (RVA), and degree of gelatinization upon freeze-thaw stability and textural properties as cooked rice. Chukanbohonno 14 was the highest in gelatinization temperature and enthalpy by DSC, followed by Koshihikari and Nipponbare. On the other hand, Tomohikari and Hoshiyutaka were low in gelatinization temperature and endothermic energy according to DSC. Koshihikari showed high in peak viscosity, low in cooled at 50°C viscosity, and low in gel firmness, whereas Tomohikari as well as high-amylose rice was high in cooled at 50°C viscosity and gel firmness. Textural analysis of cooked rice indicated that good tasting rice was soft and high in adhesiveness as cooked rice. Firmness of Chukanbohonno 14 was between that of Koshihikari and Himenomochi, and its adhesiveness was higher than that of Tomohikari. Hence, tasting grade was related to gelatinization and retrogradation properties, and good tasting rice was high in gelatinization temperature and endothermic energy as measured by DSC, and high in viscosity and low in gel firmness. Upon cooking, good tasting rice was high in degree of gelatinization, low in retrogradation by freeze-thaw treatment, and high in increase of degree of gelatinization upon reheating.
Since the Kyoto meeting on global warming, the environmental problem has been reported very often on television or in the newspaper, and has been discussed. In these discussions, disposal of plastics, especially from various viewpoints, such as the dearth of refuse disposal places, dioxin generation, environmental beautification, and protection of an ecosystem, is important. At the place of work or the home, separate collection of garbage is advancing quickly. An environmental problem has come to be felt as a familiar problem also in everyday life. One direction in which solutions to this problem are progressing is that used plastics are being collected for material-recycling and for thermal recycling as fuel. As a fundamental approach, develop ment of a biodegradable plastic was studied and various biodegradable plastics have been developed. Among these plastics, polylactate is receiving the most attention because it is made from biomass and it is effective for a continuously developing society. It is thought that a world wide market for polylactic acid can be developed.