Purification and characterization of extremely thermostable {beta}-mannanase, {beta}-mannosidase, and {alpha}-galactosidase from the hyperthermophilic eubacterium Thermotoga neapolitana 5068
- North Carolina State Univ., Raleigh, NC (United States); and others
Thermostable and thermoactive {beta}-mannanase (1,4-{beta}-D-mannan mannanohydrolase [EC 3.2.1.78]), {beta}-mannosidase ({beta}-D-mannopyranoside hydrolase [EC 3.2.1.25]), and {alpha}-galactosidase ({alpha}-D-galactoside galactohydrolase [EC 3.2.1.22]) were purified to homogeneity from cell extracts and extracellular culture supernatants of the hyperthermophilic eubacterium Thermotoga neapolitana 5068 grown on guar gum-based media. The {beta}-mannanase was an extracellular monomeric enzyme with a molecular mass of 65 kDa. The optimal temperature for activity was 90 to 92{degrees}C, with half-lives (t{sub {1/2}}) of 34 h at 85{degrees}C, 13 h at 90{degrees}C, and 35 min at 100{degrees}C. The {beta}-mannosidase and {alpha}-galactosidase were found primarily in cell extracts. The {beta}-mannosidase was a homodimer consisting of approximately 100-kDa molecular mass subunits. The optimal temperature for activity was 87{degrees}C, with t{sub {1/2}} of 18 h at 85{degrees}C, 42 min at 90{degrees}C, and 2 min at 98{degrees}C. The {alpha}-galactosidase was a 61-kDa monomeric enzyme with a temperature optimum of 100 to 103{degrees}C and t{sub {1/2}} of 9 h at 85{degrees}C, 2 h at 90{degrees}C, and 3 min at 100{degrees}C. These enzymes represent the most thermostable and thermoactive versions of these types yet reported and probably act synergistically to hydrolyze extracellular galactomannans to monosaccharides by T. neapolitana for nutritional purposes. The significance of such substrates in geothermal environments remains to be seen. 50 refs., 6 figs., 6 tabs.
- OSTI ID:
- 530721
- Journal Information:
- Applied and Environmental Microbiology, Vol. 63, Issue 1; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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