Biochemical characterization of neutral trehalase activity in Saccharomyces boulardii |
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Authors: | de Andrade Antero SR dos Santos Raquel G Nicoli Jacques R Neves Maria J |
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Institution: | 1.Laboratório de Radiobiologia, Centro de Desenvolvimento da Tecnologia Nuclear/Comiss?o Nacional de Energia Nuclear (CDTN/CNEN), Belo Horizonte, Minas Gerais, Brazil ;2.Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil ; |
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Abstract: | Lyophilized cells of the non-pathogenic yeast Saccharomyces boulardii are used in many countries for the treatment of several types of diarrhoea and other gastrointestinal diseases. Although
the cells must be viable, their mechanism of action is unknown. The disaccharide trehalose is a protectant against several
forms of environmental stress in yeast and is involved in maintaining cell viability. There is no information on the enzymes
involved in degradation of trehalose in S. boulardii. The aim of the present study was to characterize trehalase activity in this yeast. Cells of S. boulardii grown in glucose exhibited neutral trehalase activity only in the exponential phase. Acidic trehalase was not detected in
glucose medium. Cells grown in trehalose exhibited acid and neutral trehalase activities at all growth stages, particularly
in the exponential phase. The optimum pH and temperature values for neutral trehalase activity were determined as 6.5 and
30 °C respectively, the half-life being approximately 3 min at 45 °C. The relative molecular mass of neutral trehalase is
80 kDa and the K
m 6.4 mM (±0.6). Neutral trehalase activity at pH 6.5 was weakly inhibited by 5 mM EDTA and strongly inhibited by ATP, as well
as the divalent ions Cu++, Fe++ and Zn++. Enzyme activity was stimulated by Mg++ and Ca++ only in the absence of cAMP. The presence of cAMP with no ion additions increased activity by 40%.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Neutral trehalase Saccharomyces boulardii yeast |
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