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Intrinsic halotolerance of the psychrophilic alpha-amylase from Pseudoalteromonas haloplanktis

Srimathi, Soundararajan LU ; Jayaraman, Gurunathan; Feller, Georges; Danielsson, Bengt LU and Narayanan, Paranji R. (2007) In Extremophiles 11(3). p.505-515
Abstract
The halotolerance of a cold adapted alpha-amylase from the psychrophilic bacterium Pseudoalteromonas haloplanktis (AHA) was investigated. AHA exhibited hydrolytic activity over a broad range of NaCl concentrations (0.01-4.5 M). AHA showed 28% increased activity in 0.5-2.0 M NaCl compared to that in 0.01 M NaCl. In contrast, the corresponding mesophilic (Bacillus amyloliquefaciens) and thermostable (B. licheniformis) alpha-amylases showed a 39 and 46% decrease in activity respectively. Even at 4.5 M NaCl, 80% of the initial activity was detected for AHA, whereas the mesophilic and thermostable enzymes were inactive. Besides an unaltered fluorescence emission and secondary structure, a 10 degrees C positive shift in the temperature optimum,... (More)
The halotolerance of a cold adapted alpha-amylase from the psychrophilic bacterium Pseudoalteromonas haloplanktis (AHA) was investigated. AHA exhibited hydrolytic activity over a broad range of NaCl concentrations (0.01-4.5 M). AHA showed 28% increased activity in 0.5-2.0 M NaCl compared to that in 0.01 M NaCl. In contrast, the corresponding mesophilic (Bacillus amyloliquefaciens) and thermostable (B. licheniformis) alpha-amylases showed a 39 and 46% decrease in activity respectively. Even at 4.5 M NaCl, 80% of the initial activity was detected for AHA, whereas the mesophilic and thermostable enzymes were inactive. Besides an unaltered fluorescence emission and secondary structure, a 10 degrees C positive shift in the temperature optimum, a stabilization factor of > 5 for thermal inactivation and a Delta T-m of 8.3 degrees C for the secondary structure melting were estimated in 2.7 M NaCl. The higher activation energy, half-life time and T-m indicated reduced conformational dynamics and increased rigidity in the presence of higher NaCl concentrations. A comparison with the sequences of other halophilic alpha-amylases revealed that AHA also contains higher proportion of small hydrophobic residues and acidic residues resulting in a higher negative surface potential. Thus, with some compromise in cold activity, psychrophilic adaptation has also manifested halotolerance to AHA that is comparable to the halophilic enzymes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
halotolerance, halophilic, acidic protein, Pseudoalteromonas haloplanktis alpha-amylase, psychrophilic, stability
in
Extremophiles
volume
11
issue
3
pages
505 - 515
publisher
Springer
external identifiers
  • wos:000246353300010
  • scopus:34248392177
ISSN
1433-4909
DOI
10.1007/s00792-007-0062-5
language
English
LU publication?
yes
id
f998d8cb-73ae-46b1-910f-f58100c25f8e (old id 660501)
date added to LUP
2007-12-19 09:47:55
date last changed
2017-11-19 03:29:41
@article{f998d8cb-73ae-46b1-910f-f58100c25f8e,
  abstract     = {The halotolerance of a cold adapted alpha-amylase from the psychrophilic bacterium Pseudoalteromonas haloplanktis (AHA) was investigated. AHA exhibited hydrolytic activity over a broad range of NaCl concentrations (0.01-4.5 M). AHA showed 28% increased activity in 0.5-2.0 M NaCl compared to that in 0.01 M NaCl. In contrast, the corresponding mesophilic (Bacillus amyloliquefaciens) and thermostable (B. licheniformis) alpha-amylases showed a 39 and 46% decrease in activity respectively. Even at 4.5 M NaCl, 80% of the initial activity was detected for AHA, whereas the mesophilic and thermostable enzymes were inactive. Besides an unaltered fluorescence emission and secondary structure, a 10 degrees C positive shift in the temperature optimum, a stabilization factor of > 5 for thermal inactivation and a Delta T-m of 8.3 degrees C for the secondary structure melting were estimated in 2.7 M NaCl. The higher activation energy, half-life time and T-m indicated reduced conformational dynamics and increased rigidity in the presence of higher NaCl concentrations. A comparison with the sequences of other halophilic alpha-amylases revealed that AHA also contains higher proportion of small hydrophobic residues and acidic residues resulting in a higher negative surface potential. Thus, with some compromise in cold activity, psychrophilic adaptation has also manifested halotolerance to AHA that is comparable to the halophilic enzymes.},
  author       = {Srimathi, Soundararajan and Jayaraman, Gurunathan and Feller, Georges and Danielsson, Bengt and Narayanan, Paranji R.},
  issn         = {1433-4909},
  keyword      = {halotolerance,halophilic,acidic protein,Pseudoalteromonas haloplanktis alpha-amylase,psychrophilic,stability},
  language     = {eng},
  number       = {3},
  pages        = {505--515},
  publisher    = {Springer},
  series       = {Extremophiles},
  title        = {Intrinsic halotolerance of the psychrophilic alpha-amylase from Pseudoalteromonas haloplanktis},
  url          = {http://dx.doi.org/10.1007/s00792-007-0062-5},
  volume       = {11},
  year         = {2007},
}