IMIS | Flanders Marine Institute
 

Flanders Marine Institute

Platform for marine research

IMIS

Publications | Institutes | Persons | Datasets | Projects | Maps
[ report an error in this record ]basket (0): add | show Print this page

Cold-adapted β-galactosidase from the Antarctic psychrophile Pseudoalteromonas haloplanktis
Hoyoux, A.; Jennes, I.; Dubois, P.; Genicot, S.; Dubail, F.; François, J.-M.; Baise, E.; Feller, G.; Gerday, C. (2001). Cold-adapted β-galactosidase from the Antarctic psychrophile Pseudoalteromonas haloplanktis. Appl. Environ. Microbiol. 67(4): 1529-1535. dx.doi.org/10.1128/AEM.67.4.1529-1535.2001
In: Applied and Environmental Microbiology. American Society for Microbiology: Washington. ISSN 0099-2240; e-ISSN 1098-5336, more
Peer reviewed article  

Available in  Authors 

Keyword
    Marine

Authors  Top 
  • Hoyoux, A.
  • Jennes, I.
  • Dubois, P., more
  • Genicot, S.
  • Dubail, F.
  • François, J.-M.
  • Baise, E.
  • Feller, G., more
  • Gerday, C., more

Abstract
    The β-galactosidase from the Antarctic gram-negative bacterium Pseudoalteromonas haloplanktis TAE 79 was purified to homogeneity. The nucleotide sequence and the NH2-terminal amino acid sequence of the purified enzyme indicate that the β-galactosidase subunit is composed of 1,038 amino acids with a calculated M r of 118,068. This β-galactosidase shares structural properties with Escherichia coli β-galactosidase (comparable subunit mass, 51% amino sequence identity, conservation of amino acid residues involved in catalysis, similar optimal pH value, and requirement for divalent metal ions) but is characterized by a higher catalytic efficiency on synthetic and natural substrates and by a shift of apparent optimum activity toward low temperatures and lower thermal stability. The enzyme also differs by a higher pI (7.8) and by specific thermodynamic activation parameters. P. haloplanktis β-galactosidase was expressed in E. coli, and the recombinant enzyme displays properties identical to those of the wild-type enzyme. Heat-induced unfolding monitored by intrinsic fluorescence spectroscopy showed lower melting point values for both P. haloplanktiswild-type and recombinant β-galactosidase compared to the mesophilic enzyme. Assays of lactose hydrolysis in milk demonstrate that P. haloplanktis β-galactosidase can outperform the current commercial β-galactosidase from Kluyveromyces marxianusvar. lactis, suggesting that the cold-adapted β-galactosidase could be used to hydrolyze lactose in dairy products processed in refrigerated plants.

All data in the Integrated Marine Information System (IMIS) is subject to the VLIZ privacy policy Top | Authors