Document Detail

Gene cloning and biochemical characterization of a catalase from Gluconobacter oxydans.
MedLine Citation:
PMID:  21317031     Owner:  NLM     Status:  Publisher    
Gluconobacter oxydans has a large number of membrane-bound dehydrogenases linked to the respiratory chain that catalyze incomplete oxidation of a wide range of organic compounds by oxidative fermentation. Because the respiratory chain is a primary site of reactive oxygen species (ROS) production, the bacterium is expected to have a high capacity to detoxify nascent ROS. In the present study, a gene that encodes a catalase of G. oxydans, which might act as a potential scavenger of H(2)O(2), was cloned, and the expression product (termed rGoxCat) was characterized biochemically. rGoxCat is a heme b-containing tetrameric protein (molecular mass, 320kDa) consisting of identical subunits. The recombinant enzyme displayed a strong catalase activity with a k(cat) of 6.28×10(4)s(-1) and a K(m) for H(2)O(2) of 61mM; however, rGoxCat exhibited no peroxidase activity. These results, along with the phylogenetic position of the enzyme, provide conclusive evidence that rGoxCat is a monofunctional, large-subunit catalase. The enzyme was most stable in the pH range of 4-9, and greater than 60% of the original activity was retained after treatment at pH 3.0 and 40°C for 1h. Moreover, the enzyme exhibited excellent thermostability for a catalase from a mesophilic organism, retaining full activity after incubation for 30min at 70°C. The observed catalytic properties of rGoxCat, as well as its stability in a slightly acidic environment, are consistent with its role in the elimination of nascent H(2)O(2) in a bacterium that produces a large amount of organic acid via oxidative fermentation.
Haruhiko Yamaguchi; Keigo Sugiyama; Miho Hosoya; Seiji Takahashi; Toru Nakayama
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-11
Journal Detail:
Title:  Journal of bioscience and bioengineering     Volume:  -     ISSN:  1347-4421     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-2-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888800     Medline TA:  J Biosci Bioeng     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2010. Published by Elsevier B.V.
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