Linked Life Data

10654839

Source:http://linkedlifedata.com/resource/pubmed/id/10654839

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2000-2-11
pubmed:abstractText
The peroxidase from Coprinus cinereus (CPX) catalyzed oxidative oligomerization of 4-chloroaniline (4-CA) forming several products: N-(4-chlorophenyl)-benzoquinone monoamine (dimer D), 4,4'-dichloroazobenzene (dimer E); 2-(4-chloroanilino)-N-(4-chlorophenyl)-benzoquinone (trimer F); 2-amino-5-chlorobenzoquinone-di-4-chloroanil (trimer G); 2-(4-chloroanilino)-5-hydroxybenzoquinone-di-4-chloroanil (tetramer H) and 2-amino-5-(-4-chlroanilino)-benzoquinone-di-4-chloroanil (tetramer 1). In the presence of 4-CA and H2O2, CPX was irreversibly inactivated within 10 min. Inactivation of CPX in the presence of H2O2 was a time-dependent, first-order process when the concentration of 4-CA was varied between 0 and 2.5 mM. The apparent dissociation constant (Ki) for CPX and 4-CA was 0.71 mM. The pseudo-first order rate constant for inactivation (k(inact)), was 1.15 x 10(-2) s(-1). Covalent incorporation of 20 mole 14C-4-CA per mole of inactivated CPX was observed. The partition ratio was about 2200 when either 4-CA or H2O2 was used as the limiting substrate. These results show that 4-CA is a metabolically activated inactivator (i.e. a suicide substrate). Unmodified heme and hydroxymethyl heme were isolated from native, 4-CA-inactivated and H2O2-incubated CPX. Inactivation resulted in significant losses in both heme contents. Analysis of tryptic peptides from 4-CA-inactivated CPX by MALDI-TOF/ MS and UV-VIS spectrophotometry suggested that trimer G and tetramer H were the major 4-CA derivatives that were covalently bound, including to a peptide (MGDAGF-SPDEVVDLLAAHSLASQEGLNSAIFR) containing the heme binding site. These studies show that heme destruction and covalent modification of the polypeptide chain are both important for the inactivation of CPX. These results were compared with similar studies on 4-CA-inactivated horseradish peroxidase (HRP) and bovine lactoperoxidase (LPO) during the oxidation of 4-CA.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0009-2797
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
123
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
197-217
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Inactivation of Coprinus cinereus peroxidase by 4-chloroaniline during turnover: comparison with horseradish peroxidase and bovine lactoperoxidase.
pubmed:affiliation
Division of Biochemical Toxicology, National Center for Toxicological Research, FDA, Jefferson, AR 72079, USA. cchang@nctr.fda.gov
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.