Author： Alkorta F. Amarita F. Rodriguez-Fernandez C.
Publisher： Academic Press
ISSN： 0023-6438
Source： Lebensmittel-Wissenschaft und -Technologie, Vol.26, Iss.4, 1993-08, pp. : 329-333
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Abstract
β-galactosidase activity in extracts of Enterobacter agglomerans biotype 5 was studied after precipitation with 229 g/L of ammonium sulphate. This enzyme had maximum activity at pH 7.6. Using p-nitrophenyl-β-d-galactopyranoside as substrate, Vmax and Km were estimated, and the effect of d-galactose, d-glucose and l-histidine on β-galactosidase activity were studied. Addition of alcohols resulted in a reduction of the β-galactosidase activity. Addition of the chelating agent EDTA produced inactivation. After treatment with EDTA, activity could be restored to some extent upon addition of Mg2+ and Ca2+. Enzymatic activity vs. temperature was studied, obtaining the maximum activity at 40°C and activation energy (Ea) was calculated giving a value of 64.85 kJ/mol. Preincubation was carried out at different times and temperatures, 10 min at 40°C resulted in a loss of enzymatic activity. If preincubated for 15s at 65°C the enzyme only retained 0.1 of the enzymic activity.
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