Switch to
Predicate | Object |
---|---|
rdf:type | |
lifeskim:mentions | |
pubmed:issue |
7
|
pubmed:dateCreated |
1988-8-1
|
pubmed:abstractText |
An enzyme capable of activating protein C has been purified 60-fold from the venom of the Southern copperhead snake (Agkistrodon contortrix) by ion-exchange and gel filtration chromatography. The purified enzyme consists of a single polypeptide with an apparent molecular weight of 37,000. The isoelectric point of the protein C activator was determined to be 6.3 when measured by chromatofocusing. The enzyme was inhibited by p-nitrophenyl p-guanidinobenzoate, phenylmethanesulfonyl fluoride, and D-Phe-Pro-Arg-CH2Cl but was not affected by cysteine-directed reagents or by metal chelators. These results suggest that the enzyme is a serine protease. Protein C activator was capable of hydrolyzing the thrombin substrate tosyl-Gly-Pro-Arg-p-nitroanilide (TGPRpNA), and steady-state kinetic studies determined that the Km for amidolysis of this substrate was 1.1 mM while the Vmax was 66 s-1. The activator demonstrated considerable substrate specificity since the amidolysis of D-Phe-Pip-Arg-pNA, D-Ile-Pro-Arg-pNA, Bz-Ile-Glu-Gly-Arg-pNA, D-Val-Leu-Arg-pNA, and pyrGlu-Pro-Arg-pNA was less than 10% of that of TGPRpNA when measured under identical conditions using 1.0 mM substrate concentrations. The enzyme appears to be thrombin-like in its preference for arginyl as compared to lysyl chloromethyl ketones as well as by its inhibition by benzamidine and p-aminobenzamidine. However, the substrate specificity of the activator is distinguished from alpha-thrombin in that it does not clot fibrinogen and does not react with antithrombin III or hirudin.(ABSTRACT TRUNCATED AT 250 WORDS)
|
pubmed:grant | |
pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
|
pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Agkistrodon venoms,
http://linkedlifedata.com/resource/pubmed/chemical/Crotalid Venoms,
http://linkedlifedata.com/resource/pubmed/chemical/Oligopeptides,
http://linkedlifedata.com/resource/pubmed/chemical/Protein C,
http://linkedlifedata.com/resource/pubmed/chemical/protein C activator peptide
|
pubmed:status |
MEDLINE
|
pubmed:month |
Apr
|
pubmed:issn |
0006-2960
|
pubmed:author | |
pubmed:issnType |
Print
|
pubmed:day |
5
|
pubmed:volume |
27
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
2558-64
|
pubmed:dateRevised |
2007-11-14
|
pubmed:meshHeading | |
pubmed:year |
1988
|
pubmed:articleTitle |
Characterization of a protein C activator from the venom of Agkistrodon contortrix contortrix.
|
pubmed:affiliation |
American Red Cross, Biomedical Research and Development Division, Rockville, Maryland 20855.
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
|