Linked Life Data

2271532

Source:http://linkedlifedata.com/resource/pubmed/id/2271532

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
33
pubmed:dateCreated
1991-2-25
pubmed:abstractText
The three phospholipase A2 isoenzymes from Naja nigricollis venom inhibit blood coagulation with different potencies. The strongly anticoagulant basic isoenzyme CM-IV inhibits the prothrombinase complex, whereas the weakly anticoagulant isoenzymes CM-I and CM-II do not. To determine the role of enzymatic activity of the phospholipases in the inhibition of prothrombinase, we varied the time of incubation of each of these isoenzymes with the prothrombinase complex. The inhibition by CM-IV did not increase with time of incubation. CM-I and CM-II failed to inhibit the complex, even with complete hydrolysis of phospholipids in the assay mixture. After alkylation of its active-site histidine, CM-IV lost 97% of its enzymatic activity but retained 60% of its inhibitory potency on prothrombinase. CM-IV also inhibited prothrombinase activity in the absence of phospholipids, whereas CM-I and CM-II did not. The inhibition of the prothrombinase complex by CM-IV is thus not due to its binding to or hydrolysis of phospholipids. The kinetics of CM-IV inhibition of the prothrombinase complex in both the presence and absence of phospholipids was noncompetitive. This inhibition can be explained by binding of CM-IV to either factor Va or Xa, or both, to inhibit the complex. CM-IV differs from previously described nonenzymatic anticoagulants that are proteinase inhibitors or that inhibit the coagulation complexes by interfering with the binding of clotting factors to phospholipids. We conclude that the basic enzyme, CM-IV, inhibits the prothrombinase complex by a novel mechanism independent of enzymatic activity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7742-6
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
The basic phospholipase A2 from Naja nigricollis venom inhibits the prothrombinase complex by a novel nonenzymatic mechanism.
pubmed:affiliation
Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't