The effects of the environmental temperature during the early development of seeds on the characteristics of the endosperm starch were investigated using near-isogenic lines and induced mutants of rice. The components of starch and pasting characteristics of starch granules varied by the environmental temperature. The lower temperature increased the amylose content and the ratios of short chain to long chain of amylopectin in endosperm starch. Moreover, the starch granules of rice plants grown under the lower temperature were more gelatinized than those grown under the higher temperature.

View full abstract

An attempt was made to isolate thermophilic bacteria growing at temperatures above 60°C and secreting β-amylase using immunoreaction between anti-jS-amylase serum or IgG prepared from Bacillus cereus β-amylase and unknown amylases. Among 170 strains isolated from various sources like soils, hot springs, etc., only one strain was selected by dot-ELISA and Western blotting methods. Morphological and physiological properties of the strain indicated that the strain belongs to Bacillus stearothermophilus. The amylase fraction was obtained from the culture filtrate by salting out with ammoniumsulf ate (0.7 saturation) and purified by ion-exchange chromatography on DEAE-cellulofine A-500 and gel filtration on Sephadex G-100. Further, by first protein liquid chromatography (FPLC) on Mono-Q HR5/5 column, the three amylase fractions (Fracts. I, II, and III) were obtained. Analysis of their hydrolytic products from starch showed that the amylases are classified to aamylase. Their optimum pH and temperature were around 60 and 70°C, respectively, and the enzymes were stable around 70°C. Among the three a-amylases only Fract. III had immunoreactivity with anti-β-amylase serum or IgG, and gave different products in starch hydrolysis; mainly glucose from soluble starch, and maltose and maltotriose from raw starch.

View full abstract

The action of cyclodextrin glucanotransferase (CGT-ase) on α-glucosylfluoride (α-GF) or α-maltosylfluoride(α-G2F)in the presence of 9-cyclodextrin(CD)or α-CD, respectively, was investigated for the purpose of γ-CD production. The optimum condition of the γ-CD production from the mixture of α-GF and β-CD by CGT-ase was α-GF: 30 mM, β-CD: 10 mM, CGT-ase from Bacillus megaterium: 60 unit/ml, incubation at 40°C for 30 min. In this condition, the amount of γ-CDproduction was 1.7 mM and the ratio of α-and γ-CD production was 1 : 2. In the reaction system of α-G2F and α-CD, CGT-ase from B, macerans produced more γ-CD than did the enzyme from B. megaterium. But the ratio of α-, β-, and γ-CD formation was almost the same as that from starch.

View full abstract

The distribution, intraparticle diffusion, and axial dispersion coefficients of maltooligosaccharides with degrees of polymerization (d, p.) of 1 to 5 and 7 on hydrophilic vinyl polymer gel, Toyopearl HW-405, were determined by the moment analysis of the elution curves of the saccharides . The dependencies of the coefficients on d, p. were obtained . By using the parameters evaluated, the bed height required to separate almost completely the maltooligosaccharides with d, p, of i and i+1(i=1 to 6) was calculated. The parallel pore model was applicable for the gel to estimate the intraparticle diffusion coefficients of the saccharides .

View full abstract

1. Starch granules were prepared from mature kernels of several single mutants, double- and triple-mutant combinations of waxy (wx) gene with other endosperm genes, and their normal counterpart in the inbred 0h43 maize (Zea mays L.) background. Starches of the mutants containing the wx gene comprised almost 100% amylopectin. jS-Amylase limit dextrins prepared from the starches were successively debranched by isoamylase and pullulanase, and followed by quantitative gel-filtration on Toyopearl HW54SF. The unit chain-length distribution of amylopectins of the normal and wx starches were similar. Amylopectin of the amylose-extender ; waxy (ae ; wx) mutant had an increased proportion of long B chains and a decreased proportion of short B chains, compared with wx amylopectin, whereas amylopectin of dull ; waxy (du ; wx) mutant had a decreased proportion of long B chains and an increased proportion of short B chains. Therefore, the ae ; wx and du ; wx amylopectins were novel. Amylopectin of the ae ; du; wx mutant belonged to the du ; wx type instead of the ae ; wx type. 2. Starch granules were prepared from rice (Oryza sativa L.) endosperms of dull (du), sugary (sug), and high-amylose (ae) mutants. The amylose content of the du starch was half as low as that of the nonmutant (normal) one. The sug starch contained more amylose than the normal starch. The starch in the ae mutants was characterized by a higher content of amylose and loosely branched amylopectin with longer chains compared with the normal starch.

View full abstract

This paper is based on the commemorative lecture on the occasion of receiving the Reward of Japanese Society of Starch Science of 1988, and comprises the following five parts. 1. Process for Producing Cyclodextrins (CDs): A series of industrial production of CDs developed by the author is described. The author made full examinations on the reaction of producing CDs by cyclodextrin glucanotransferase (CGT-ase) from B. macerans without using any organic solvent, and clarified the effective conditions on CDs production on an industrial scale. This process was developed based upon said results of the research, consisting of non immobilized ultrafiltration membrane reactor system in which the cyclization reaction by CGT-ase is effected in a very low concentration of substrate (starch) as the first process, the reverse osmosis membrane system to concentrate the reaction product, and the spray dryer system to pulverize the reaction product. 2. Circumstances of Actual Production: The industrial production of CDs was started by Ensuiko Sugar Refining Co., in 1982. This part describes the details of how Branched-CD and CD-Polymer have come to be produced in the said company since then. 3. Present State of Application of CD: Application of CDs to foods, cosmetics, toiletaries, and resin products is described. 4. Trends of Development of New CD Materials: This part describes the trends of development of chemical modified CDs or enzymatic modified CDs with the purpose of improving the solubility of natural CDs including alpha-, beta-, gamma-CDs, as well as trends of development in various CD polymers. Particularly, there are descriptions of separation-fractionation agent of CD polymers and uses in analytical chemistry. 5. CD Productions and Developments Outside Japan: Industrial production of CDs had been made solely in Japan, but lately has also been begun in many other countries . The present situations pertaining to the producing and developing of CDs in Hungary, West Germany, France, and U. S. A, are described.

View full abstract

The distribution of components and hydrolysis patterns by glucoamylase were investigated for the starches prepared from maize (Zea mays L.) having either one or two of recessive endosperm genes, namely waxy (wx), dull (du), sugary-1 (sul), sugary-2 (su2), and amylose-extender (ae). Properties of residual ae and sue starches after glucoamylase hydrolysis were also examined. The wx gene decreased the amylose content and increased starch granule susceptibility to glucoamylase. When the du gene was combined with the sul or sue gene, amylose content of the starches increased. The ratio of short chains of amylopectin increased through the introduction of the du or sul genes. The proportions of amylose, intermediate fraction, and long chains of amylopectin increased when the ae gene was introduced. The ae starch granules had lower susceptibility to glucoamylase than that of the normal maize, and very slow stage of hydrolysis appeared after 80-85% degradation. The residual ae starch on the slow stage accumulated the low-molecular-weight materials which were not shown in the original starch. Similar materials were present in the redidual sue starches, but not in those of the normal maize. Properties of these materials were investigated, and the relation to crystal region in the starch granules was discussed. Starch granules were prepared from seeds of Job's tears [hatomugi, Coix lacryma jobi L. mayuen (Roman) Stapf, and juzudama, Coix lacryma jobi L.] and sorghum [Sorghum bicolor(L.) Moench] which were collected in Japan, Korea, and Indonesia. The distribution of components, gelatinization characteristics, and susceptibility to amylases of the starches were investigated. The properties of hatomugi and juzudama starches were similar to those of waxy and normal type of maize starches, respectively. Sorghum starches of nonwaxy type showed wide variation in the amylose content. Starch granules of all sample seeds had higher susceptibility to amylases than that of normal maize.

View full abstract

(1) One form and three forms (GI, GII, and GIII) of glucoamylases were purified from crude commercial preparation of Aspergillus niger and Rhizopus delemar, respectively, to be homogenous on disc- and SDS-gel electrophoresis and free from a-amylase and phosphatase. Neither purified glucoamylase from A. niger nor R. delemar could completely hydrolyze various kinds of starches because of the presence of phosphate esters attached to C-3 or C-6 of glucosyl residue, and left a limit-dextrin of large-molecular weight. The concomitant actions of a-amylase and phosphatase with the glucoamylases were found to be necessary for complete hydrolysis of these starches. (2) R. delemar GIII was suggested to have a specific affinity site, "starch-binding site, " for high-molecular-weight substrates from the results of kinetic study and modification with chymotrypsin. GI and GII were suggested to be derived from GIII by the post-secretional modification. (3) Aspergillus sp. K-27 produced the enzyme (s) which degraded well the raw starches. Glucoamylase and a-amylase were separated and purified from the culture filtrate of the fungus. The former seemed to have the "starch-binding site, " based on the results of partial proteolysis and kinetic studies. The latter showed low activity on raw starches but synergistically enhanced the degradation of starch granules with glucoamylase. The removal of the starch-binding site from glucoamylase reduced the ability of raw-starch degradation and abolished the synergistic effect with a-amylase. These results suggested that the starch-binding site plays an importantrole in raw-starch hydrolysis.

View full abstract