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Purification and characterization of glucoamylase of Aspergillus terreus NA‐170 mutant
Author(s) -
Ghosh Anuradha,
Chatterjee Banhisikha,
Das Arati
Publication year - 1991
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1991.tb02973.x
Subject(s) - aspergillus terreus , sephadex , mutant , enzyme , starch , chemistry , catabolite repression , hydrolysis , biochemistry , yield (engineering) , aspergillus niger , size exclusion chromatography , enzyme assay , materials science , metallurgy , gene
A catabolite‐derepressed mutant strain of Aspergillus terreus NA‐170 was isolated by multi‐step mutagenesis. The mutant produced an appreciable yield of glucoamylase in the culture medium. The enzyme was purified and was shown to be homogeneous. It hydrolysed successive glucose residues from the non‐reducing end of starch molecules. The purified enzyme had an optimum pH of 5·0 and was stable over the pH range 3·0–7·0. It was highly active over a broad temperature range, 30–75°C, with optimal activity at 60°C. The molecular weight was 70 000 as determined by Sephadex G‐200 filtration. The enzyme showed a decrease in K m values with increasing chain length of the substrate molecule.