Calcium ion-dependent increase in thermostability of dextran glucosidase from Streptococcus mutans
| Autor: | Kobayashi, Momoko, Hondoh, Hironori, Mori, Haruhide, Saburi, Wataru, Okuyama, Masayuki, Kimura, Atsuo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Escherichia coli
Streptococcus mutans/enzymology Bacterial Proteins/chemistry Models Molecular Recombinant Proteins/genetics two - step irreversible deactivation Enzyme Stability/drug effects Glucosidases/chemistry Kinetics Dextrans/metabolism Magnesium/pharmacology Binding Sites Glucosidases/genetics Plasmids Streptococcus mutans/genetics calcium - binding site Bacterial Proteins/metabolism Protein Structure Secondary Cloning Molecular Magnesium/metabolism Calcium/metabolism Cations Divalent/metabolism Bacterial Proteins/genetics Recombinant Proteins/chemistry dextran glucosidase thermostability Oligosaccharides/metabolism Calcium/pharmacology Cations Divalent/pharmacology Recombinant Proteins/metabolism glycoside hydrolase family 13 Glucosidases/metabolism |
| Zdroj: | Bioscience, biotechnology, and biochemistry. 75(8):1557-1563 |
| ISSN: | 1347-6947 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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