ISSN:
1432-072X
Schlagwort(e):
Ectothiorhodospira halochloris
;
Osmoregulation
;
Betaine
;
Phototrophic bacteria
;
Haloalkaliphilic bacteria
;
Trehalase
;
Trehalose
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Trehalase, which hydrolyzes the disaccharide trehalose to α-d-glucose was isolated and partially purified (124-fold) from the phototrophic halo-alkaliphilic bacterium Ectothiorhodospira halochloris. The molecular mass was determined to be 480,000 and the isoelectric point pH 5.6. Temperature optimum was found to be 40°C and the pH-optimum 7.8–8.1. In spite of its high K m-value of 0.5 M, trehalase of E. halochloris was shown to be specific for trehalose. Trehalase is activated by phosphate which is, however, not involved in the reaction mechanism. The enzyme is activated by the compatible solute betaine and inhibited by salts. In the presence of betaine the K m-value is lowered from 0.5 M to 0.16 M; moreover, betaine partially protects enzymatic activity from salt inhibition. The findings indicate that betaine might regulate the trehalose level in the cells by affecting trehalase activity.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00245272
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