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Kinetic behaviour and stability of Escherichia coli ATCC27257 alkaline phosphatase immobilised in soil humates
Author(s) -
Pilar María C,
Ortega Natividad,
PerezMateos Manuel,
Busto María D
Publication year - 2003
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.1301
Subject(s) - alkaline phosphatase , chemistry , enzyme , phosphatase , soil enzyme , enzyme assay , escherichia coli , chromatography , thermal stability , nuclear chemistry , biochemistry , organic chemistry , gene
Alkaline phosphatase (EC 3.1.3.1) extracted from Escherichia coli ATCC27257 was immobilised by co‐flocculation with soil humates in the presence of Ca 2+ . The effects of time, temperature, pH and concentration of enzyme and support on immobilisation were studied. Between 58 and 92% of the added phosphatase was strongly bound to the humates, depending on the conditions of immobilisation used. Some characteristics of the humate–phosphatase complexes and of the free enzyme were compared. The enzymatic complexes showed values of K m (2.22 m M ) and activation energy (33.4 kJ mol −1 ) similar to those of the free enzyme (2.00 m M and 27.6 kJ mol −1 ). The pH/activity profiles revealed no change in terms of shape or optimum pH (10.5) upon immobilisation of alkaline phosphatase. However, the immobilised enzyme showed maximal activity in the range of 80–100 °C, while the free enzyme had its highest activity at 60 °C. The thermal stability of alkaline phosphatase was enhanced by complexation to the soil humates. © 2003 Society of Chemical Industry