Purification and characterisation of an extracellular phytase from Aspergillus niger 11T53A9
Braz. j. microbiol
;
40(4): 795-807, Oct.-Dec. 2009. graf, tab
Artigo
em Inglês
| 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.
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Aspergillus niger
/
Cromatografia em Gel
/
Enzimas
/
Sulfato de Amônio
Idioma:
Inglês
Revista:
Braz. j. microbiol
Assunto da revista:
Microbiologia
Ano de publicação:
2009
Tipo de documento:
Artigo
País de afiliação:
Brasil
/
Alemanha
Instituição/País de afiliação:
CEFET/BR
/
Federal Research Institute of Nutrition and Food/DE
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