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Calcium ion-dependent increase in thermostability of dextran glucosidase from Streptococcus mutans.
Title: | Calcium ion-dependent increase in thermostability of dextran glucosidase from Streptococcus mutans. |
Authors: | Kobayashi, Momoko Browse this author | Hondoh, Hironori Browse this author | Mori, Haruhide Browse this author →KAKEN DB | Saburi, Wataru Browse this author →KAKEN DB | Okuyama, Masayuki Browse this author →KAKEN DB | Kimura, Atsuo Browse this author →KAKEN DB |
Keywords: | dextran glucosidase | thermostability | two - step irreversible deactivation | calcium - binding site | glycoside hydrolase family 13 |
Issue Date: | 2011 |
Publisher: | 日本農芸化学会 |
Journal Title: | Bioscience, biotechnology, and biochemistry |
Volume: | 75 |
Issue: | 8 |
Start Page: | 1557 |
End Page: | 1563 |
PMID: | 21821929 |
Abstract: | Dextran glucosidase from Streptococcus mutans (SmDG), which belongs to glycoside hydrolase family 13 (GH13), hydrolyzes the non-reducing terminal glucosidic linkage of isomaltooligosaccharides and dextran. Thermal deactivation of SmDG did not follow the single exponential decay but rather the two-step irreversible deactivation model, which involves an active intermediate having 39% specific activity. The presence of a low concentration of CaCl2 increased the thermostability of SmDG, mainly due to a marked reduction in the rate constant of deactivation of the intermediate. The addition of MgCl2 also enhanced thermostability, while KCl and NaCl were not effective. Therefore, divalent cations, particularly Ca2+, were considered to stabilize SmDG. On the other hand, CaCl2 had no significant effect on catalytic reaction. The enhanced stability by Ca2+ was probably related to calcium binding in the β→α loop 1 of the (β/α)(8) barrel of SmDG. Because similar structures and sequences are widespread in GH13, these GH13 enzymes might have been stabilized by calcium ions. |
Type: | article |
URI: | http://hdl.handle.net/2115/48146 |
Appears in Collections: | 農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 木村 淳夫
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