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Calcium ion-dependent increase in thermostability of dextran glucosidase from Streptococcus mutans.

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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
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
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)

Submitter: 木村 淳夫

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