| Kinetics of inhibition of platelet calpain II by human kininogens. | |
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MedLine Citation:
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PMID: 2396995 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The plasma kininogens, high-molecular-mass and low-molecular-mass kininogens, are the most potent plasma inhibitors of platelet calpain. We explored the kinetic mechanisms for kininogen inhibition of calpain by comparing calpain inactivation by human high-molecular-mass kininogen (HK) and human low-molecular-mass kininogen (LK). With a [14C]methylated alpha-casein substrate, the inhibition of calpain by HK did not follow classic Michaelis-Menten kinetics. With the use of a fluorogenic assay with the dipeptide substrate for calpain, 3-carboxypropionyl-leucyltyrosine 7-(4-methyl)coumarylamide, the inhibition by HK and LK fitted a kinetic model of tight-binding inhibition. LK was found to be a non-competitive inhibitor of platelet calpain with a Ki of 2.7 nM. HK showed mixed non-competitive inhibition of calpain with a Ki of 2.3 nM in the absence of substrate and Ki of 0.71 nM in the presence of saturating substrate, almost 4-fold tighter than LK. Proteolysis of HK by plasma and tissue kallikreins did not influence its ability to inhibit calpain. Digestion of the HK light chain by Factor XIa also did not alter its calpain-inhibitory function. These studies indicate that the kininogens are tight-binding non-competitive inhibitors of platelet calpain, the inhibitory domain in each case being mainly on the heavy chain. The light chain of HK appears to influence its kinetic behaviour. |
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Authors:
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H N Bradford; A H Schmaier; R W Colman |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Biochemical journal Volume: 270 ISSN: 0264-6021 ISO Abbreviation: Biochem. J. Publication Date: 1990 Aug |
Date Detail:
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Created Date: 1990-10-11 Completed Date: 1990-10-11 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 83-90 Citation Subset: IM |
Affiliation:
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Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Blood Platelets
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enzymology* Calpain / antagonists & inhibitors* Caseins / metabolism Humans Kinetics Kininogens / pharmacology* Molecular Weight Peptide Fragments / pharmacology Structure-Activity Relationship |
| Grant Support | |
ID/Acronym/Agency:
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HL01615/HL/NHLBI NIH HHS; HL24365/HL/NHLBI NIH HHS; HL35553/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Caseins; 0/Kininogens; 0/Peptide Fragments; EC 3.4.22.-/Calpain |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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