Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis
peer reviewed The thermal stability of the cold-active alpha-amylase (AHA) secreted by the Antarctic bacterium Alteromonas haloplanctis has been investigated by intrinsic fluorescence, circular dichroism, and differential scanning calorimetry. It was found that this heat-labile enzyme is the largest...
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ftorbi:oai:orbi.ulg.ac.be:2268/16180 2024-04-21T07:49:58+00:00 Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis Feller, Georges d'Amico, D. Gerday, Charles 1999-04-06 https://orbi.uliege.be/handle/2268/16180 https://doi.org/10.1021/bi982650 en eng American Chemical Society urn:issn:0006-2960 urn:issn:1520-4995 https://orbi.uliege.be/handle/2268/16180 info:hdl:2268/16180 doi:10.1021/bi982650+ scopus-id:2-s2.0-0033528657 info:pmid:10194383 restricted access http://purl.org/coar/access_right/c_16ec info:eu-repo/semantics/restrictedAccess Biochemistry, 38 (14), 4613-9 (1999-04-06) Life sciences Biochemistry biophysics & molecular biology Sciences du vivant Biochimie biophysique & biologie moléculaire journal article http://purl.org/coar/resource_type/c_6501 info:eu-repo/semantics/article peer reviewed 1999 ftorbi https://doi.org/10.1021/bi982650 2024-03-27T14:54:55Z peer reviewed The thermal stability of the cold-active alpha-amylase (AHA) secreted by the Antarctic bacterium Alteromonas haloplanctis has been investigated by intrinsic fluorescence, circular dichroism, and differential scanning calorimetry. It was found that this heat-labile enzyme is the largest known multidomain protein exhibiting a reversible two-state unfolding, as demonstrated by the recovery of DeltaHcal values after consecutive calorimetric transitions, a DeltaHcal/DeltaHeff ratio close to unity, and the independence of unfolding thermodynamic parameters of scan rates. By contrast, the mesophilic alpha-amylases investigated here (from porcine pancreas, human salivary glands, yellow meal beetle, Bacillus amyloliquefaciens, and Bacillus licheniformis) unfold irreversibly according to a non-two-state mechanism. Unlike mesophilic alpha-amylases, the melting point of AHA is independent of calcium and chloride binding while the allosteric and structural functions of these ions are conserved. The thermostability of AHA at optimal conditions is characterized by a Tm of 43.7 degrees C, a DeltaHcal of 238 kcal mol-1, and a DeltaCp of 8.47 kcal mol-1 K-1. These values were used to calculate the Gibbs free energy of unfolding over a wide range of temperatures. This stability curve shows that (a) the specific DeltaGmax of AHA [22 cal (mol of residue)-1] is 4 times lower than that of mesophilic alpha-amylases, (b) group hydration plays a crucial role in the enzyme flexibility at low temperatures, (c) the temperature of cold unfolding closely corresponds to the lower limit of bacterial growth, and (d) the recombinant heat-labile enzyme can be expressed in mesophilic hosts at moderate temperatures. It is also argued that the cold-active alpha-amylase has evolved toward the lowest possible conformational stability of its native state. Article in Journal/Newspaper Antarc* Antarctic University of Liège: ORBi (Open Repository and Bibliography) |
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Open Polar |
collection |
University of Liège: ORBi (Open Repository and Bibliography) |
op_collection_id |
ftorbi |
language |
English |
topic |
Life sciences Biochemistry biophysics & molecular biology Sciences du vivant Biochimie biophysique & biologie moléculaire |
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Life sciences Biochemistry biophysics & molecular biology Sciences du vivant Biochimie biophysique & biologie moléculaire Feller, Georges d'Amico, D. Gerday, Charles Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
topic_facet |
Life sciences Biochemistry biophysics & molecular biology Sciences du vivant Biochimie biophysique & biologie moléculaire |
description |
peer reviewed The thermal stability of the cold-active alpha-amylase (AHA) secreted by the Antarctic bacterium Alteromonas haloplanctis has been investigated by intrinsic fluorescence, circular dichroism, and differential scanning calorimetry. It was found that this heat-labile enzyme is the largest known multidomain protein exhibiting a reversible two-state unfolding, as demonstrated by the recovery of DeltaHcal values after consecutive calorimetric transitions, a DeltaHcal/DeltaHeff ratio close to unity, and the independence of unfolding thermodynamic parameters of scan rates. By contrast, the mesophilic alpha-amylases investigated here (from porcine pancreas, human salivary glands, yellow meal beetle, Bacillus amyloliquefaciens, and Bacillus licheniformis) unfold irreversibly according to a non-two-state mechanism. Unlike mesophilic alpha-amylases, the melting point of AHA is independent of calcium and chloride binding while the allosteric and structural functions of these ions are conserved. The thermostability of AHA at optimal conditions is characterized by a Tm of 43.7 degrees C, a DeltaHcal of 238 kcal mol-1, and a DeltaCp of 8.47 kcal mol-1 K-1. These values were used to calculate the Gibbs free energy of unfolding over a wide range of temperatures. This stability curve shows that (a) the specific DeltaGmax of AHA [22 cal (mol of residue)-1] is 4 times lower than that of mesophilic alpha-amylases, (b) group hydration plays a crucial role in the enzyme flexibility at low temperatures, (c) the temperature of cold unfolding closely corresponds to the lower limit of bacterial growth, and (d) the recombinant heat-labile enzyme can be expressed in mesophilic hosts at moderate temperatures. It is also argued that the cold-active alpha-amylase has evolved toward the lowest possible conformational stability of its native state. |
format |
Article in Journal/Newspaper |
author |
Feller, Georges d'Amico, D. Gerday, Charles |
author_facet |
Feller, Georges d'Amico, D. Gerday, Charles |
author_sort |
Feller, Georges |
title |
Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
title_short |
Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
title_full |
Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
title_fullStr |
Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
title_full_unstemmed |
Thermodynamic Stability of a Cold-Active Alpha-Amylase from the Antarctic Bacterium Alteromonas Haloplanctis |
title_sort |
thermodynamic stability of a cold-active alpha-amylase from the antarctic bacterium alteromonas haloplanctis |
publisher |
American Chemical Society |
publishDate |
1999 |
url |
https://orbi.uliege.be/handle/2268/16180 https://doi.org/10.1021/bi982650 |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Biochemistry, 38 (14), 4613-9 (1999-04-06) |
op_relation |
urn:issn:0006-2960 urn:issn:1520-4995 https://orbi.uliege.be/handle/2268/16180 info:hdl:2268/16180 doi:10.1021/bi982650+ scopus-id:2-s2.0-0033528657 info:pmid:10194383 |
op_rights |
restricted access http://purl.org/coar/access_right/c_16ec info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1021/bi982650 |
_version_ |
1796933873071816704 |