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Purification and Characterization of a Thermophilic α‐Amylase of Aspergillus niger van Tieghem
Author(s) -
Ramasesh N.,
Sreekantiah K. R.,
Murthy V. S.
Publication year - 1982
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19820340807
Subject(s) - aspergillus niger , thermophile , maltose , starch , amylase , chemistry , fractionation , sephadex , enzyme , chromatography , specific activity , biochemistry , enzyme assay , hydrolysis , food science
The exocellular α‐amylase of a strain of Aspergillus niger van Tieghem (elaborating both dextrifying and saccharifying thermophilic amylases) was purified to homogeneity. Purification was achieved by providing cultural conditions for the organism to preferentially synthesize α‐amylase and fractionation of the culture filtrate by DEAE‐Sephadex chromatography. Its purity was established by gel electrophoresis and confirmed by sedimentation studies. The molecular weight of the enzyme was 56,230. Its Km values on different starches, temperature and pH optima for activity and energy of activation were established. Compared to literature values for other fungal α‐amylases, this enzyme exhibited a lower energy of activation, increased tolerance to lower pH and enhanced affinity to starch, highlighting its potential industrial application. While Ag + , Pb 2+ , Hg + , Al 3+ and EDTA inhibited the activity of the enzyme, Ca 2+ enhanced its activity, apart from conferring thermal stability and lowered activation energy. The product of its action on starch were maltooligosaccharides, maltose and glucose.