Linked Life Data

9162031

Source:http://linkedlifedata.com/resource/pubmed/id/9162031

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
22
pubmed:dateCreated
1997-6-27
pubmed:abstractText
Heparin cofactor II (HCII) is presumed to be a physiological inhibitor of the serine proteinase thrombin. The reaction between HCII and thrombin is quite unique, because it involves an unusual HCII-reactive site loop sequence of Leu444-Ser445, requires the presence of glycosaminoglycans for optimal activity and involves a protein-protein interaction besides the reactive site loop-active site interaction characteristic of serine proteinase inhibitor-serine proteinase pairs. Two mutations at a unique HCII residue, Arg200 --> Ala or Glu, were generated by site-directed mutagenesis. The mutations did not alter either HCII binding to heparin-Sepharose or HCII inhibition of thrombin in the presence of heparin or dermatan sulfate, suggesting that Arg200 is not part of the glycosaminoglycan binding site of HCII. In the absence of glycosaminoglycan, there was a significant increase in alpha-thrombin inhibition by the Arg200 mutants as compared with wild type recombinant HCII (wt-rHCII), whereas inhibition rates with chymotrypsin were identical. Inhibition of gammaT-thrombin, which lacks anion-binding exosite 1 ((ABE-1), the region of alpha-thrombin that interacts with the acidic domain of HCII), was significantly reduced compared with alpha-thrombin, but the reduction was more dramatic for the Arg200-rHCII mutants. Hirugen, which binds to ABE-1 of alpha-thrombin, also diminished inhibition of alpha-thrombin by the Arg200-rHCII mutants to nearly wt-rHCII levels. Both Arg200-rHCII mutants had significantly increased ka values as compared with wt-rHCII, whereas the kd rates were unchanged. Collectively, these results suggest that the improved inhibitory activity of the Arg200-rHCII mutants is mediated by enhanced interactions between the acidic domain and ABE-1, resulting in an increased HCII-thrombin association rate.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
30
pubmed:volume
272
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14074-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Arginine 200 of heparin cofactor II promotes intramolecular interactions of the acidic domain. Implication for thrombin inhibition.
pubmed:affiliation
Department of Pharmacology, The University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.