Characterization of Halomonas sp. Strain H11 α-Glucosidase Activated by Monovalent Cations and Its Application for Efficient Synthesis of α- d -Glucosylglycerol
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Media type:
E-Article
Title:
Characterization of Halomonas sp. Strain H11 α-Glucosidase Activated by Monovalent Cations and Its Application for Efficient Synthesis of α- d -Glucosylglycerol
Published:
American Society for Microbiology, 2012
Published in:
Applied and Environmental Microbiology, 78 (2012) 6, Seite 1836-1845
Language:
English
DOI:
10.1128/aem.07514-11
ISSN:
0099-2240;
1098-5336
Origination:
Footnote:
Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
An α-glucosidase (HaG) with the following unique properties was isolated from
<jats:named-content content-type="genus-species">Halomonas</jats:named-content>
sp. strain H11: (i) high transglucosylation activity, (ii) activation by monovalent cations, and (iii) very narrow substrate specificity. The molecular mass of the purified HaG was estimated to be 58 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). HaG showed high hydrolytic activities toward maltose, sucrose, and
<jats:italic>p</jats:italic>
-nitrophenyl α-
<jats:sc>d</jats:sc>
-glucoside (
<jats:italic>p</jats:italic>
NPG) but to almost no other disaccharides or malto-oligosaccharides higher than trisaccharides. HaG showed optimum activity to maltose at 30°C and pH 6.5. Monovalent cations such as K
<jats:sup>+</jats:sup>
, Rb
<jats:sup>+</jats:sup>
, Cs
<jats:sup>+</jats:sup>
, and NH
<jats:sub arrange="stack">4</jats:sub>
<jats:sup arrange="stack">+</jats:sup>
increased the enzymatic activity to 2- to 9-fold of the original activity. These ions shifted the activity-pH profile to the alkaline side. The optimum temperature rose to 40°C in the presence of 10 mM NH
<jats:sub arrange="stack">4</jats:sub>
<jats:sup arrange="stack">+</jats:sup>
, although temperature stability was not affected. The apparent
<jats:italic>
K
<jats:sub>m</jats:sub>
</jats:italic>
and
<jats:italic>k</jats:italic>
<jats:sub>cat</jats:sub>
values for maltose and
<jats:italic>p</jats:italic>
NPG were significantly improved by monovalent cations. Surprisingly,
<jats:italic>k</jats:italic>
<jats:sub>cat</jats:sub>
/
<jats:italic>
K
<jats:sub>m</jats:sub>
</jats:italic>
for
<jats:italic>p</jats:italic>
NPG increased 372- to 969-fold in their presence. HaG used some alcohols as acceptor substrates in transglucosylation and was useful for efficient synthesis of α-
<jats:sc>d</jats:sc>
-glucosylglycerol. The efficiency of the production level was superior to that of the previously reported enzyme
<jats:named-content content-type="genus-species">Aspergillus niger</jats:named-content>
α-glucosidase in terms of small amounts of by-products. Sequence analysis of HaG revealed that it was classified in glycoside hydrolase family 13. Its amino acid sequence showed high identities, 60%, 58%, 57%, and 56%, to
<jats:named-content content-type="genus-species">Xanthomonas campestris</jats:named-content>
WU-9701 α-glucosidase,
<jats:named-content content-type="genus-species">Xanthomonas campestris</jats:named-content>
pv. raphani 756C oligo-1,6-glucosidase,
<jats:named-content content-type="genus-species">Pseudomonas stutzeri</jats:named-content>
DSM 4166 oligo-1,6-glucosidase, and
<jats:named-content content-type="genus-species">Agrobacterium tumefaciens</jats:named-content>
F2 α-glucosidase, respectively.
</jats:p>