Document Detail


Gene analysis and enzymatic properties of thermostable beta-glycosidase from Pyrococcus kodakaraensis KOD1.
MedLine Citation:
PMID:  16232586     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
A beta-glycosidase with broad substrate specificity was identified from a hyperthermophilic archaeon, Pyrococcus kodakaraensis KOD1. The gene encoding beta-glycosidase (Pk-gly) consists of 1449 nucleotides corresponding to a polypeptide of 483 amino acids. The protein showed similarity with other beta-glycosidases from family-1 glycosyl hydrolases, in particular, it showed high identity to beta-mannosidase from P. furiosus (55.7%), beta-glycosidase from Sulfolobus solfataricus (42.7%) and beta-glucosidase from P. furiosus (41.9%). The cloned gene was expressed in Escherichia coli and the recombinant protein was purified. The beta-glycosidase showed optimal activity at pH 6.5 and at an extremely high temperature of 100 degrees C, and had a half-life of 18 h at 90 degrees C. The beta-glycosidase hydrolyzed various pNp-beta-glycopyranosides, with kcat K(m) values in the order of pNp-beta-glucopyranoside = pNp-beta-mannopyranoside > pNp-beta-galactopyranoside > pNp-beta-xylopyranoside. pNp-beta-mannopyranoside was the substrate exhibiting the lowest K(m) value [0.254 mM] with a kcat K(m) ratio comparable to that of pNp-beta-glucopyranoside. This substrate specificity was distinct from previously reported beta-glycosidases. We observed that the region in PK-Gly corresponding to the fifth alpha-helix and beta-strand region of beta-glycosidase from S. solfataricus, which constitutes a large portion of the channel for substrate incorporation, displayed a chimeric structure, with the N-terminal region similar to beta-glycosidases and the C-terminal region similar to beta-mannosidases. An exo-type hydrolytic activity and transglycosylation activity were also observed towards cellooligomers.
Authors:
S Ezaki; K Miyaoku; K Nishi; T Tanaka; S Fujiwara; M Takagi; H Atomi; T Imanaka
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of bioscience and bioengineering     Volume:  88     ISSN:  1389-1723     ISO Abbreviation:  J. Biosci. Bioeng.     Publication Date:  1999  
Date Detail:
Created Date:  2005-10-19     Completed Date:  2005-10-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888800     Medline TA:  J Biosci Bioeng     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  130-5     Citation Subset:  -    
Affiliation:
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
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