Linked Life Data

15823018

Source:http://linkedlifedata.com/resource/pubmed/id/15823018

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
2005-4-12
pubmed:databankReference
pubmed:abstractText
The large subunit catalase HPII from Escherichia coli can be truncated by proteolysis to a structure similar to small subunit catalases. Mass spectrometry analysis indicates that there is some heterogeneity in the precise cleavage sites, but approximately 74 N-terminal residues, 189 C-terminal residues, and a 9-11-residue internal fragment, including residues 298-308, are removed. Crystal structure refinement at 2.8 A reveals that the tertiary and quaternary structure of the native enzyme is retained with only very subtle changes despite the loss of 36% of the sequence. The truncated variant exhibits a 1.8 times faster turnover rate and enhanced sensitivity to high concentrations of H(2)O(2), consistent with easier access of the substrate to the active site. In addition, the truncated variant is more sensitive to inhibition, particularly by reagents such as aminotriazole and azide which are larger than substrate H(2)O(2). The main channel leading to the heme cavity is largely unaffected by the truncation, but the lateral channel is shortened and its entrance widened by removal of the C-terminal domain, providing an explanation for easier access to the active site. Opening of the entrance to the lateral channel also opens the putative NADPH binding site, but NADPH binding could not be demonstrated. Despite the lack of bound NADPH, the compound I species of both native and truncated HPII are reduced back to the resting state with compound II being evident in the absorbance spectrum only of the heme b-containing H392A variant.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5597-605
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:15823018-Binding Sites, pubmed-meshheading:15823018-Catalase, pubmed-meshheading:15823018-Catalytic Domain, pubmed-meshheading:15823018-Crystallography, X-Ray, pubmed-meshheading:15823018-Escherichia coli, pubmed-meshheading:15823018-Escherichia coli Proteins, pubmed-meshheading:15823018-Genetic Variation, pubmed-meshheading:15823018-Heme, pubmed-meshheading:15823018-Hydrogen Peroxide, pubmed-meshheading:15823018-Kinetics, pubmed-meshheading:15823018-Models, Molecular, pubmed-meshheading:15823018-Peptide Fragments, pubmed-meshheading:15823018-Peptide Hydrolases, pubmed-meshheading:15823018-Protein Structure, Quaternary, pubmed-meshheading:15823018-Protein Structure, Tertiary, pubmed-meshheading:15823018-Protein Subunits, pubmed-meshheading:15823018-Spectrometry, Mass, Electrospray Ionization
pubmed:year
2005
pubmed:articleTitle
Characterization of a large subunit catalase truncated by proteolytic cleavage.
pubmed:affiliation
Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't