Purification and characterisation of an extracellular phytase from Aspergillus niger 11T53A9

Brazilian Journal of Microbiology

Ralf Greiner²  Lucineia Gomes Da Silva¹  Sonia Couri¹ 

[1] ,Federal Research Institute of Nutrition and Food Max Rubner-Institute Department of Food and Bio Process EngineeringKarlsruhe,Germany

关键词: Aspergillus niger;    phytate-degrading enzyme;    phytate;    phytase;   

DOI  :  10.1590/S1517-83822009000400010

来源: SciELO

【 摘 要 】

An extracellular phytase from Aspergillus niger 11T53A9 was purified about 51-fold to apparent homogeneity with a recovery of 20.3% 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 55°C. 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 37°C. 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.

【 授权许可】

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