Purification and characterisation of an extracellular phytase from Aspergillus niger 11T53A9
Braz. j. microbiol
;
40(4): 795-807, Oct.-Dec. 2009. graf, tab
Article
in English
| LILACS
| ID: lil-528162
ABSTRACT
An extracellular phytase from Aspergillus niger 11T53A9 was purified about 51-fold to apparent homogeneity with a recovery of 20.3 percent referred to the phytase activity in the crude extract. Purification was achieved by ammonium sulphate precipitation, ion chromataography and gel filtration. The purified enzyme behaved as a monomeric protein with a molecular mass of about 85 kDa and exhibited maximal phytate-degrading activity at pH 5.0. Optimum temperature for the degradation of phytate was 55ºC. The kinetic parameters for the hydrolysis of sodium phytate were determined to be K M = 54 µmol l-1 and k cat = 190 sec-1 at pH 5.0 and 37ºC. The purified enzyme was rather specific for phytate dephosphorylation. It was shown that the phytase preferably dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 to finally Ins(2)P.
Full text:
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Index:
LILACS (Americas)
Main subject:
Aspergillus niger
/
Chromatography, Gel
/
Enzymes
/
Ammonium Sulfate
Language:
English
Journal:
Braz. j. microbiol
Journal subject:
Microbiology
Year:
2009
Type:
Article
Affiliation country:
Brazil
/
Germany
Institution/Affiliation country:
CEFET/BR
/
Federal Research Institute of Nutrition and Food/DE
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