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Evidence that the glucoamylases and alpha-amylase secreted by Aspergillus niger are proteolytically processed products of a precursor enzyme.

Dubey, A. K. and Suresh Babu, C. V. and Kavitha, R. and Karanth, N. G. and Umesh Kumar, S. (2000) Evidence that the glucoamylases and alpha-amylase secreted by Aspergillus niger are proteolytically processed products of a precursor enzyme. FEBS letters, 471 (2-3). pp. 251-5. ISSN 0014-5793

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Abstract

A 125-kDa starch hydrolysing enzyme of Aspergillus niger characterised by its ability to dextrinise and saccharify starch [Suresh et al. (1999) Appl. Microbiol. Biotechnol. 51, 673-675] was also found to possess activity towards raw starch. Segregation of these activities in the 71-kDa glucoamylase and a 53-kDa alpha-amylase-like enzyme supported by antibody cross-reactivity studies and the isolation of mutants based on assay screens for the secretion of particular enzyme forms revealed the 125-kDa starch hydrolysing enzyme as their precursor. N-terminal sequence analysis further revealed that the 71-kDa glucoamylase was the N-terminal product of the precursor enzyme. Immunological cross reactivity of the 53-kDa amylase with antibodies raised against the precursor enzyme but not with the 71- and 61-kDa glucoamylase antibodies suggested that this enzyme activity is represented by the C-terminal fragment of the precursor. The N-terminal sequence of the 53-kDa protein showed similarity to the reported Taka amylase of Aspergillus oryzae. Antibody cross-reactivity to a 10-kDa non-enzymic peptide and a 61-kDa glucoamylase described these proteins as products of the 71-kDa glucoamylase. Identification of only the precursor starch hydrolysing enzyme in the protein extracts of fungal protoplasts suggested proteolytic processing in the cellular periplasmic space as the cause for the secretion of multiple forms of amylases by A. niger.

Item Type: Article
Uncontrolled Keywords: Glucoamylase; K-Amylase; Amylase precursor; Raw starch hydrolysis; Aspergillus niger
Subjects: 500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology > 04 Fungi
500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 16 Enzyme Chemistry
Divisions: Fermentation Technology and Bioengineering
Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 27 Nov 2008 05:39
Last Modified: 30 May 2012 11:10
URI: http://ir.cftri.com/id/eprint/2167

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