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- 저자 : ( Osaka University ) (검색결과 3 건)
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FUJIWARA, SHINSUKE,KAKIHARA, HIROFUMI,KIM, BYUNG WOO,LEJEUNE, ANDRE,KANEMOTO, MITSUHIDE,SAKAGUCHI, KENJI,IMANAKA, TADAYUKI 동의대학교 기초과학연구소 1993 基礎科學硏究論文集 Vol.3 No.1
Cyclodextrin glucanotransferase (CGTase; EC 2.4.1.19) is produced mainly by Bacillus strains. CGTase from Bacillus macerans IFO3490 produces α-cyclodextrin as the major hydrolysis product from starch, where as thermostable CGTase from Bacillus stearothermophilus NO2 produces α- and β- cyclodextrins. To analyze the cyclization characteristics of CGTase, we cloned different types of CGTase genes and constructed chimeric-genes. CGTase genes from these two strains were cloned in Bacillus subtilis NA-1 by using pTB523 as a vector plasmid, and their nucleotide sequences were determined. Three CGTase genes (cgt-1, cgt-5, and cgt-232) were isolated from B. stearothermophilus NO2. Nucleotide sequence analysis revealed that the three CGTase genes have different nucleotide sequences encoding the same amino acid sequence. Base substitutions were found at the third letter of five codons among the three genes. Each open reading frame was composed of 2,133 bases, encoding 711 amino acids containing 31 amino acids as a signal sequence. The molecular weight of the mature enzyme was estimated to be 75,374. The CGTase gene (cgtM) of B. macerans IFO3490 was composed of 2,142 bases, encoding 714 amino acids containing 27 residues as a signal sequence. The molecular weight of the mature enzyme was estimated to be 74,008. The sequence determined in this work was quite different from that reported previously by other worker. From data on the three-dimensional structure of a CGTase, seven kinds of chimeric CGTase genes were constructed by using cgy-1 from B. stearothermophilus NO2 and cgtM from B. macerans IFO3490. We examined the characteristics of these chimeric enzymes on cyclodextrin production and thermostability. It was found that the cyclization reaction was conferred by the NH₂-terminal region of CGTase and that the thermostability of some chimeric enzymes was lower than that of the parental CGTases.
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Jong-Moon Park,Ki-Young Kim,Kyoung-Kyun Kim,Osaka University,Makoto Takahashi,Myung-Hoon Oh 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.3
Although the welding zone of direct bonding between a TiAl alloy and SCM440 can be obtained by friction welding, martensitictransformation and the formation of intermetallic compounds (IMCs) and cracks result in a lower tensile strengthof the joints relative to those of other welding techniques. Insert metals were used as a buff er layer to relieve stress whileincreasing the bond strength. In this study, the microstructure and mechanical properties on welded joints of a TiAl alloy andSCM440 with various insert metals, were investigated. The TiAl/Cu/SCM440 and TiAl/Ni/SCM440 joints were fabricatedusing a servo-motor-type friction welding machine. As a result, it was confi rmed that the formation of a welding fl ash wasdependent on the insert metal type, and the strength of the base metal. At the TiAl/Cu/SCM440 interface, the formation ofIMCs CuTiAl and Cu 2 TiAl was observed at TiAl/Cu, while no IMC formation was observed at Cu/SCM440. On the otherhand, at the TiAl/Ni/SCM440 interface, several IMCs with more than 100 μm thickness were found, and roughly two compositions,viz., Ti 2 NiAl 3 and TiNi 2 Al, were observed at the TiAl/Ni interface. At the Ni/SCM440 interface, 10 μm-thickFeNi and others were found.
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