Truncation of N- and C-terminal regions of Streptococcus mutans dextranase enhances catalytic activity = 말단부위를 절단한 후 활성이 급격하게 증가하는 구강내 존재하는 덱스트란 분해효소

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Title
Truncation of N- and C-terminal regions of Streptococcus mutans dextranase enhances catalytic activity = 말단부위를 절단한 후 활성이 급격하게 증가하는 구강내 존재하는 덱스트란 분해효소
Author(s)
Young Min Kim; R Shimizu; H Nakai; H Mori; M Okuyama; S M Kang; Z Fujimoto; K Funane; D Kim; A Kimura
Bibliographic Citation
Applied Microbiology and Biotechnology, vol. 91, no. 2, pp. 329-339
Publication Year
2011
Abstract
Multiple forms of native and recombinant endo-dextranases (Dexs) of the glycoside hydrolase family (GH) 66 exist. The GH 66 Dex gene from Streptococcus mutans ATCC 25175 (SmDex) was expressed in Escherichia coli. The recombinant full-size (95.4 kDa) SmDex protein was digested to form an 89.8 kDa isoform (SmDex90). The purified SmDex90 was proteolytically degraded to more than seven polypeptides (23-70 kDa) during long storage. The protease-insensitive protein was desirable for the biochemical analysis and utilization of SmDex. GH 66 Dex was predicted to comprise four regions from the N- to C-termini: N-terminal variable region (N-VR), conserved region (CR), glucan-binding site (GBS), and C-terminal variable region (C-VR). Five truncated SmDexs were generated by deleting N-VR, GBS, and/or C-VR. Two truncation-mutant enzymes devoid of C-VR (TM-NCGΔ) or N-VR/C-VR (TM-ΔCGΔ) were catalytically active, thereby indicating that N-VR and C-VR were not essential for the catalytic activity. TM-ΔCGΔ did not accept any further protease-degradation during long storage. TM-NCGΔ and TM-ΔCGΔ enhanced substrate hydrolysis, suggesting that N-VR and C-VR induce hindered substrate binding to the active site.
Keyword
Glycoside hydrolase family 66Limited proteolysisTruncationEndo-dextranase
ISSN
0175-7598
Publisher
Springer
DOI
http://dx.doi.org/10.1007/s00253-011-3201-y
Type
Article
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1. Journal Articles > Journal Articles
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