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Purification and some properties of a novel raw starch‐digesting amylase from Aspergillus carbonarius
Author(s) -
Okolo Bartholomew N,
Ire Francis S,
Ezeogu Lewis I,
Anyanwu Chukwudi U,
Odibo Frederick J C
Publication year - 2001
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/1097-0010(200102)81:3<329::aid-jsfa815>3.0.co;2-3
Subject(s) - starch , amylopectin , chemistry , maltose , amylase , chromatography , maltotriose , amylose , hydrolysis , alpha amylase , enzyme , food science , sucrose , enzyme assay , pullulan , bran , biochemistry , polysaccharide , raw material , organic chemistry
A medium was developed to obtain the maximum yield of raw starch‐digesting amylase from Aspergillus carbonarius (Bainier) Thom IMI 366159 in submerged culture with raw starch as the sole carbon source. The amylase was purified to apparent homogeneity by sucrose concentration and ion exchange chromatography on S‐ and Q‐Sepharose (fast flow) columns. SDS‐PAGE revealed two migrating protein bands corresponding to relative molecular masses of 31.6 and 32 KDa. The enzyme was optimally active at pH 6.0–7.0 and 40 °C, was uninfluenced across a relatively broad pH range of 3.0–9.0 and retained over 85% activity between 30 and 80 °C after 20 min incubation. The enzyme was strongly activated by Co 2+ and only slightly by Fe 2+ , while Ca 2+ , Hg 2+ , EDTA and N ‐bromosuccinamide elicited significant repression of the enzyme activity. The enzyme hydrolysed amylopectin ( K m 0.194 mg ml −1 ), glycogen ( K m 0.215 mg ml −1 ), pullulan ( K m 0.238 mg ml −1 ), amylose ( K m 0.256 mg ml −1 ) and raw potato starch ( K m 0.260 mg ml −1 ), forming predominantly maltose and relatively smaller amounts of glucose. © 2000 Society of Chemical Industry