Journal of Applied Glycoscience
Online ISSN : 1880-7291
Print ISSN : 1344-7882
ISSN-L : 1344-7882
Volume 58 , Issue 2
Showing 1-6 articles out of 6 articles from the selected issue
  • Hiromoto Yamakawa
    2011 Volume 58 Issue 2 Pages 35-38
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: February 17, 2011
    High temperature impairs grain filling of rice by inhibiting accumulation of starch in the endosperm, making the grain appear chalky. It affects the molecular structure of a starch component, amylopectin (e.g., elongation of its chains), then hardening the texture of cooked rice. Recent comprehensive analyses such as transcriptome, proteome and metabolome which are assisted by the rice genome information revealed the key metabolic factors involved in this deterioration of rice grain by elevated temperatures. Shortage of starch (defect in starch quantity) could be caused by a combination of decreased expression of starch biosynthesis-related genes such as GBSSI and BEIIb and increased degradation of starch by induced expression of α-amylase genes. Determination of carbohydrate metabolites further suggested that sugar metabolism and ATP production are also impaired under high temperature, leading to the decrease of starch deposition. For the hardening of the texture (defect in starch quality), decreased branching of amylopectin by reduced expression of starch branching enzyme genes, especially short chain-producing BEIIb, would contribute to enrichment of its long chains. In this review, effects of high temperature on grain filling-related metabolism are summarized at the gene level.
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Regular Papers
  • Tetsuya Mori, Tomoyuki Nishimoto, Takanori Okura, Hiroto Chaen, Shigeh ...
    2011 Volume 58 Issue 2 Pages 39-46
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: January 25, 2011
    The gene encoding for a novel hydrolase, cyclic α-maltosyl-(1→6)-maltose [CMM, cyclo-{→6)-α-D-Glcp-(1→4)-α-D-Glcp-(1→6)-α-D-Glcp-(1→4)-α-D-Glcp-(1→}] hydrolase (CMMase), was cloned from the genomic library of Arthrobacter globiformis M6 and designated cmmF. The gene consisted of 1,353 bp encoding a protein of 450 amino-acids with a calculated molecular mass of 49,344 Da. The deduced amino-acid sequence showed similarities to cyclodextrinase, maltogenic amylase and neopullulanase. On the other hand, the complete sequence of the α-glucosidase gene (cmmB), which encodes an enzyme involved in the degradation of CMM, revealed that the gene consisted of 1,704 bp encoding a protein of 567 amino-acids with a calculated molecular mass of 63,014 Da. The four conserved regions common in the α-amylase family enzymes were also found in CMMase and α-glucosidase, indicating that these enzymes should be assigned to this family. The DNA sequence of 5,675 bp analyzed in this study contained another four open reading frames (ORFs), designated cmmC, cmmD, cmmE and cmmG, downstream of cmmB. CmmC, cmmD and cmmE were expected to encode proteins concerned with incorporation of CMM via cell membrane. CmmG was expected to encode a transcriptional regulator protein. CMMase gene, α-glucosidase gene and another four ORFs formed a gene cluster together with 6-α-maltosyltrasferase gene (cmmA) which encodes a CMM-forming enzyme, namely cmmABCDEFG. The results of gene analysis suggested that A. globiformis M6 has a unique starch utilization pathway via CMM.
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  • Yoshihiro Hakamada, Shoukan Arata, Shinichi Ohashi
    2011 Volume 58 Issue 2 Pages 47-51
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: January 31, 2011
    A xyloglucanase (xyloglucan-specific endo-β-1,4-glucanase [EC]), AoXEG29, was purified from Aspergillus oryzae RIB40 to 75.5-fold of its apparent homogeneity with 1.2% recovery. It was a monomeric protein with a molecular mass of approximately 29 kDa estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration and zymogram analysis. Sugar-chain staining showed a sugar chain in the purified enzyme. AoXEG29 hydrolyzed detectable amounts of xyloglucan and AZCL-xyloglucan, but not CMC, H3PO4-swollen cellulose, oat-spelt xylan, low-melting-point agarose, glucomannan, colloidal chitin, or AZCL-xylan. The optimum pH at 40°C and optimum temperature at pH 5.0 were 4.5-5.5 and 60°C, respectively. AoXEG29 was stable at pH 3-8 at 40°C for 30 min and up to 50°C at pH 5 for 20 min. The kinetic parameters Km and Vmax for the hydrolysis of tamarind xyloglucan were 2.4 mg/mL and 1,250 U/mg, respectively.
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  • Kenji Katayama, Kanefumi Kitahara, Tetsufumi Sakai, Yumi Kai, Masaru Y ...
    2011 Volume 58 Issue 2 Pages 53-59
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: March 05, 2011
    The sweet potato is recognized as a health-promoting food, owing to its richness in functional components such as dietary fiber; however, only a few studies have been conducted on resistant starch (RS) levels in the sweet potato. Now, the sweet potato is expected to have potential as a renewable resource for bio-ethanol production. The enzymatic digestibility of raw starch appears to influence the conversion rate of starch to sugar in the first step of ethanol production. In this study, the RS content of gelatinized starch, digestible starch (DS) content of raw starch and other starch properties were investigated using 21 sweet potato cultivars and lines to assess varietal variations and to estimate relationships among these starch properties. The RS content of gelatinized starch ranged between 1.8 and 9.5%. The DS content of raw starch ranged between 69.3 and 98.3%. Analysis of variance indicated that the varietal differences were significant at the 0.1% level for both the RS content and the DS content. Sweet potato starches with high amylose content and low paste viscosity showed high RS content of gelatinized starch. Starches with low pasting temperature and slow retrogradation showed high DS content of raw starch. A new breeding line, Kyukei 03284-156, contained a unique starch having the highest RS content, highest amylose content, lowest paste viscosity and abnormal granule morphology. The results of this study are expected to provide useful information to food industries that utilize sweet potato starch and to breeders that attempt to improve the RS and DS contents in sweet potato cultivars.
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  • Yohsuke Fukada, Osamu Koide, Takeshi Miura, Tohru Kobayashi, Akira Ino ...
    2011 Volume 58 Issue 2 Pages 61-66
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: March 11, 2011
    Supplementary material
    Four arabinan-degrading enzymes are produced by Bacillus subtilis JAM A-3-6, which was isolated from a subseafloor sediment core from 0.5 m below seafloor at a water depth of 1,180 m off the Shimokita Peninsula in Japan. One of the enzymes (AbnAF25) was purified from a culture broth. The molecular mass of the enzyme was around 28 kDa as judged by SDS-polyacrylamide gel electrophoresis. The optimal pH and temperature were pH 6.3 and 60°C in phosphate buffer. AbnAF25 degraded well debranched arabinan, linear arabinan, and arabino-oligosaccharaides, but not arabinoxylan, arabinogalactan or p-nitrophenyl-α-L-arabinofuranoside, which classifies the enzyme as an endo-1,5-α-L-arabinanase. The end products from linear arabinan were mainly arabinose, arabinobiose and arabinotriose. The gene for AbnAF25 was cloned and sequenced. The deduced amino acid sequence of the enzyme revealed the highest similarity to the arabinanase of B. amyloliquefaciens with 83% identity. As AbnAF25 did not show the definite characterization of a subseafloor enzyme, strain JAM A-3-6 seems to be probably dropped or co-sedimented with a soil component.
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  • Shinji Wakuta, Shigeki Hamada, Hiroyuki Ito, Ryozo Imai, Haruhide Mori ...
    2011 Volume 58 Issue 2 Pages 67-70
    Published: 2011
    Released: April 22, 2011
    [Advance publication] Released: February 18, 2011
    Rice tuberonic acid glucoside-hydrolyzing β-glucosidase (OsTAGG) produces physiologically active tuberonic acid (TA) from its glucoside (TAG). We have previously reported the identification and some properties of OsTAGG1. Here, we describe the isolation and enzymatic properties of another OsTAGG isozyme (OsTAGG2). OsTAGG2 was purified from rice by seven purification procedures with a 2,800-fold purification. Like OsTAGG1, the purified OsTAGG2 migrated as two bands with molecular masses of 40 and 26 kDa on SDS-PAGE. Results from N-terminal sequencing and peptide mass fingerprinting of both polypeptides suggested that both bands were derived from a single polypeptide. The Km and Vmax values of OsTAGG2 toward TAG were 146 μM and 38.0 μmol/min/mg, and were 4.6-fold and 2.6-fold higher than those of OsTAGG1, respectively. OsTAGG2 as well as OsTAGG1 preferentially hydrolyzed TAG among several natural glucosides used in this study. Quantitative real-time reverse transcriptase-mediated PCR analysis revealed that OsTAGG1 and OsTAGG2 are differentially expressed in response to wounding; the expression of OsTAGG1 is down-regulated, whereas that of OsTAGG2 is up-regulated by wound treatment.
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