Purification and characterization of an intracellular beta-glucosidase from a new strain of Leuconostoc mesenteroides isolated from cassava
1997
Gueguen, Y. | Chemardin, P. | Labrot, P. | Arnaud, A. | Galzy, P.
The lactic acid bacterium, Leuconostoc mesenteroides, when grown on an arbutin-containing medium, was found to produce an intracellular beta-glucosidase. The enzyme was purified by chromatofocusing, ion-exchange chromatography and gel filtration. The molecular mass of the purified intracellular beta-glucosidase, as estimated by gel filtration, was 360 kDa. The tetrameric structure of the beta-glucosidase was determined following treatment of the purified enzyme with dodecyl sulphate (SDS). The intracellular beta-glucosidase exhibited optimum catalytic activity at 50 degrees C and pH 6 with citrate-phosphate buffer, and 5.5 with phosphate buffer. The enzyme was active against glycosides with (1 leads to 4)-beta, (1 leads to 4)-alpha and (1 leads to 6)-alpha linkage configuration. From Lineweaver-Burk plots, Km values of 0.07 mmol l-1 and 3.7 mmol l-1 were found for p-nitrophenyl-beta-D-glucopyranoside and linamarin, respectively. The beta-glucosidase was competitively inhibited by glucose and by D-gluconic acid-lactone and a glucosyl transferase activity was observed in the presence of ethanol. The beta-glucosidase of Leuconostoc mesenteroides, with cyanogenic activity, could be of potential interest in cassava detoxification, by hydrolysing the cyanogenic glucosides present in cassava pulp.
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