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KMID : 0545119980080020152
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Journal of Microbiology and Biotechnology
1998 Volume.8 No. 2 p.152 ~ p.157
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Effect of C- or D-Domain Deletion on Enzymatic Properties of Cyclodextrin Glucanotransferase from Bacillus stearothermophilus NO2
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Jeon, Sung Jong
Nam, Soo Wan/Yun, Jong Won/Song, Seung Koo/Kim, Byung Woo
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Abstract
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To analyze the role of the C and D domains in the cyclization activity of cyclodextrin glucanotransferase (CGTase), two plasmids, pKB1△C300 and pKB1△D96, were constructed in which DNA regions encoding 100 and 32 amino acids, respectively, from the C and D domains of B. stearothermophilus NO2 CGTase were deleted. The mutated CGTase from the pKB1△C300 produced much lower amounts of α-, β- and γ-cyclodextrin (CD) than the parental CGTase. However, the mutated CGTase from the pKB1△D96 showed a similar production pattern of CDs to wild-type CGTase. The production ratios of the α-, β- and γ-CDs were not affected by the deletions, when compared to those of parental CGTase. The optimum temperature of the mutated CGTase from the pKB1△C300 was decreased from 60℃ to 55℃. The optimum pH of the mutated CGTase from the pKB1D96 was shifted from 6.0 to 7.0. The thermostability of the two mutant CGTases were not changed. From these results, it is suggested that the C and D domains are not related to cyclization activity directly because mutant-enzymes deleted C or D domains still possessed their activity. However, they are important for other enzymatic properties such as productivity and pH optimum as a partition of CGTase tertiary structure.
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