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Thermostable alkaline phytase from Bacillus sp. MD2: Effect of divalent metals on activity and stability.

Thi Thuy, Tran LU ; Hashim, Suhaila LU ; Gaber, Yasser LU ; Mamo, Gashaw LU ; Mattiasson, Bo LU and Hatti-Kaul, Rajni LU (2011) In Journal of Inorganic Biochemistry 105(7). p.1000-1007
Abstract
Phytate, the major source of phosphorus in seeds, exists as a complex with different metal ions. Alkaline phytases are known to dephosphorylate phytate complexed with calcium ions in contrast to acid phytases that act only on phytic acid. A recombinant alkaline phytase from Bacillus sp. MD2 has been purified and characterized with respect to the effect of divalent metal ions on the enzyme activity and stability. The presence of Ca(2+) on both the enzyme and the substrate is required for optimal activity and stability. Replacing Ca(2+) with Ba(2+), Mn(2+), Mg(2+) and Sr(2+) in the phytase resulted in the expression of >90% of the maximal activity with calcium-phytate as the substrate, while Fe(2+) and Zn(2+) rendered the enzyme inactive.... (More)
Phytate, the major source of phosphorus in seeds, exists as a complex with different metal ions. Alkaline phytases are known to dephosphorylate phytate complexed with calcium ions in contrast to acid phytases that act only on phytic acid. A recombinant alkaline phytase from Bacillus sp. MD2 has been purified and characterized with respect to the effect of divalent metal ions on the enzyme activity and stability. The presence of Ca(2+) on both the enzyme and the substrate is required for optimal activity and stability. Replacing Ca(2+) with Ba(2+), Mn(2+), Mg(2+) and Sr(2+) in the phytase resulted in the expression of >90% of the maximal activity with calcium-phytate as the substrate, while Fe(2+) and Zn(2+) rendered the enzyme inactive. On the other hand, the calcium loaded phytase showed significant activity (60%) with sodium phytate and lower activity (17-20%) with phytate complexed with only Mg(2+), Sn(2+) and Sr(2+), respectively. On replacing Ca(2+) on both the enzyme and the substrate with other metal ions, about 20% of the maximal phytase activity was obtained only with Mg(2+) and Sr(2+), respectively. Only Ca(2+) resulted in a marked increase in the melting temperature (T(m)) of the enzyme by 12-21°C, while Ba(2+), Mn(2+), Sr(2+) or Cu(2+) resulted in a modest (2-3.5°C) increase in T(m). In the presence of 1-5mM Ca(2+), the optimum temperature of the phytase activity was increased from 40°C to 70°C, while optimum pH of the enzyme shifted by 0.4-1 pH unit towards the acidic region. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Phytate, Alkaline phytase, Divalent metal ions, Differential scanning, calorimetry
in
Journal of Inorganic Biochemistry
volume
105
issue
7
pages
1000 - 1007
publisher
Elsevier
external identifiers
  • wos:000291518700010
  • pmid:21569752
  • scopus:79955779795
ISSN
1873-3344
DOI
10.1016/j.jinorgbio.2011.04.005
language
English
LU publication?
yes
id
b9554e40-bc24-4b39-aeb4-8be2c34bd495 (old id 1972598)
date added to LUP
2011-06-17 13:01:07
date last changed
2017-07-02 03:05:45
@article{b9554e40-bc24-4b39-aeb4-8be2c34bd495,
  abstract     = {Phytate, the major source of phosphorus in seeds, exists as a complex with different metal ions. Alkaline phytases are known to dephosphorylate phytate complexed with calcium ions in contrast to acid phytases that act only on phytic acid. A recombinant alkaline phytase from Bacillus sp. MD2 has been purified and characterized with respect to the effect of divalent metal ions on the enzyme activity and stability. The presence of Ca(2+) on both the enzyme and the substrate is required for optimal activity and stability. Replacing Ca(2+) with Ba(2+), Mn(2+), Mg(2+) and Sr(2+) in the phytase resulted in the expression of >90% of the maximal activity with calcium-phytate as the substrate, while Fe(2+) and Zn(2+) rendered the enzyme inactive. On the other hand, the calcium loaded phytase showed significant activity (60%) with sodium phytate and lower activity (17-20%) with phytate complexed with only Mg(2+), Sn(2+) and Sr(2+), respectively. On replacing Ca(2+) on both the enzyme and the substrate with other metal ions, about 20% of the maximal phytase activity was obtained only with Mg(2+) and Sr(2+), respectively. Only Ca(2+) resulted in a marked increase in the melting temperature (T(m)) of the enzyme by 12-21°C, while Ba(2+), Mn(2+), Sr(2+) or Cu(2+) resulted in a modest (2-3.5°C) increase in T(m). In the presence of 1-5mM Ca(2+), the optimum temperature of the phytase activity was increased from 40°C to 70°C, while optimum pH of the enzyme shifted by 0.4-1 pH unit towards the acidic region.},
  author       = {Thi Thuy, Tran and Hashim, Suhaila and Gaber, Yasser and Mamo, Gashaw and Mattiasson, Bo and Hatti-Kaul, Rajni},
  issn         = {1873-3344},
  keyword      = {Phytate,Alkaline phytase,Divalent metal ions,Differential scanning,calorimetry},
  language     = {eng},
  number       = {7},
  pages        = {1000--1007},
  publisher    = {Elsevier},
  series       = {Journal of Inorganic Biochemistry},
  title        = {Thermostable alkaline phytase from Bacillus sp. MD2: Effect of divalent metals on activity and stability.},
  url          = {http://dx.doi.org/10.1016/j.jinorgbio.2011.04.005},
  volume       = {105},
  year         = {2011},
}