Linked Life Data

12741830

Source:http://linkedlifedata.com/resource/pubmed/id/12741830

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
2003-5-13
pubmed:abstractText
Catalase (hydroperoxidase) HPII of Escherichia coli is the largest catalase so far characterized, existing as a homotetramer of 84 kDa subunits. Each subunit has a core structure that closely resembles small subunit catalases, supplemented with an extended N-terminal sequence and compact flavodoxin-like C-terminal domain. Treatment of HPII with trypsin, chymotrypsin, or proteinase K, under conditions of limited digestion, resulted in cleavage of 72-74 residues from the N-terminus of each subunit that created a homotetramer of 76 kDa subunits with 80% of wild-type activity. Longer treatment with proteinase K removed the C-terminal domain, producing a transient 59 kDa subunit which was subsequently cleaved into two fragments, 26 and 32 kDa. The tetrameric structure was retained despite this fragmentation, with four intermediates being observed between the 336 kDa native form and the 236 kDa fully truncated form corresponding to tetramers with a decreasing complement of C-termini (4, 3, 2, and 1). The truncated tetramers retained 80% of wild-type activity. The T(m) for loss of activity during heating was decreased from 85 to 77 degrees C by removal of the N-terminal sequence and to 59 degrees C by removal of the C-terminal domain, revealing the importance of the C-terminal domain in enzyme stability. The sites of cleavage were determined by N- and C-terminal sequencing, and two were located on the surface of the tetramer with a third being exposed by removal of the C-terminal domain.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
42
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5729-35
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Hydroperoxidase II of Escherichia coli exhibits enhanced resistance to proteolytic cleavage compared to other catalases.
pubmed:affiliation
Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't