Purification and characterization of Aspergillus oryzae LK-101 salt-tolerant acid protease isolated from soybean paste |
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Authors: | Si-Kyung Lee Joo-Yeon Hwang Seung Hwa Choi Sang Moo Kim |
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Affiliation: | (1) Department of Protein Chemistry and Technology, Central Food Technological Research Institute (A Constituent Laboratory of the Council of Scientific and Industrial Research), Mysore, 570 020, India; |
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Abstract: | A novel salt-tolerant acid protease was produced from Aspergillus oryzae LK-101 (AOLK-101). The AOLK-101 protease was purified to homogeneity by ammonium sulfate precipitation, DEAE-Sephadex A-50
and Sephadex G-100 chromatographies in order. The specific activity and the purification ratio of the purified protease were
2,301 unit/mg and 11.6 fold, respectively, with 25 kDa of molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrpphoresis
(SDS-PAGE). Its optimal pH and temperature were pH 6.5 and 50°C, respectively. This protease was relatively stable at pH 4.5–7.5,
below 40°C, and up to 10% salt concentration. The protease was moderately inhibited by Ag2+ and Zn2+, and strongly by ethylenediamide tetraacetic acid (EDTA) and phenylmethysulfonyl fluoride (PMSF), but activated by Cu2+ and Mn2+. Therefore, the AOLK-101 protease was a serine protease based on the influence of metal ions and inhibitors. K
m
, V
max
, k
cat
, and k
cat
/K
m
values of AOLK-101 protease for hammastein milk casein were 1.04 mg/mL, 124.84 unit/L, 163.5/sec, and 3.9×106/m·sec, respectively. |
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Keywords: | |
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