Proteolytic modification of raw-starch-digesting amylase from Bacillus circulans F-2 with subtilisin: Separation of the substrate-hydrolytic domain and the raw substrate-adsorbable domain

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Title
Proteolytic modification of raw-starch-digesting amylase from Bacillus circulans F-2 with subtilisin: Separation of the substrate-hydrolytic domain and the raw substrate-adsorbable domain
Author(s)
Chul Ho Kim; Suk Tae Kwon; H Taniguchi; Dae Sil Lee
Bibliographic Citation
Biochimica et Biophysica Acta-Proteins and Proteomics, vol. 1122, no. 3, pp. 243-250
Publication Year
1992
Abstract
Raw starch-digesting amylase (BF-2A, 93,000 Da) from Bacillus circulans F-2 was converted into two components during digestion with subtilisin. The two components were separated and designated BF-2A' (63 kDa) and BF-2B (30 kDa), respectively. BF-2A' exhibited the same hydrolysis curve for soluble starch as the original amylase (BF-2A). Moreover, the catalytic activities of original and modified enzymes were indistinguishable in K(m), V(max) and in their specific activity for soluble starch hydrolysis. However, its adsorbability and digestibility on raw starch was greatly decreased. Furthermore, the enzymatic action pattern on soluble starch was differed greatly from that of BF-2A. The stability of the enzymes decreased below pH 5.5 and at 50°C, while it was quite stable even at pH 12. On the other hand, the smaller peptide (BF-2B) could be adsorbed onto raw starch. From these results, it is suggested that the larger peptide (BF-2A') has a region responsible for the expression of the enzyme activity to hydrolyze soluble substrate, and the smaller peptide (BF-2B) plays a role on raw starch adsorption and also contributes to the original enzyme-to-enzyme stabilization. A proposed model of the raw-starch-digesting enzyme from this strain is extensively discussed.
Keyword
active siteamylaseB. circulans F-2hydrolytic domainpeptideproteolysisraw-starch-digesting amylasesubtilisin digestion
ISSN
1570-9639
Publisher
Elsevier
DOI
http://dx.doi.org/10.1016/0167-4838(92)90399-X
Type
Article
Appears in Collections:
1. Journal Articles > Journal Articles
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