1a7c
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HUMAN PLASMINOGEN ACTIVATOR INHIBITOR TYPE-1 IN COMPLEX WITH A PENTAPEPTIDE
OverviewOverview
BACKGROUND: Plasminogen activator inhibitor type 1 (PAI-1) is an important, endogenous regulator of the fibrinolytic system. Reduction of PAI-1, activity has been shown to enhance dissolution of blood clots. Like other, serpins, PAI-1 binds covalently to a target serine protease, thereby, irreversibly inactivating the enzyme. During this process the exposed, reactive-centre loop of PAI-1 is believed to undergo a conformational, change becoming inserted into beta sheet A of the serpin. Incubation with, peptides from the reactive-centre loop transform serpins into a substrate, for their target protease. It has been hypothesised that these peptides, bind to beta sheet A, thereby hindering the conformational rearrangement, leading to loop insertion and formation of the stable serpin-protease, complex. RESULTS: We report here the 1.95 A X-ray crystal structure of a, complex of a glycosylated mutant of PAI-1, PAI-1-ala335Glu, with two, molecules of the inhibitory reactive-centre loop peptide N-Ac-TVASS-NH2., Both bound peptide molecules are located between beta strands 3A and 5A of, the serpin. The binding kinetics of the peptide inhibitor to immobilised, PAI-1-Ala335Glu, as monitored by surface plasmon resonance, is consistent, with there being two different binding sites. CONCLUSIONS: This is the, first reported crystal structure of a complex formed between a serpin and, a serpin inhibitor. The localisation of the inhibitory peptide in the, complex strongly supports the theory that molecules binding in the space, between beta strands 3A and 5A of a serpin are able to prevent insertion, of the reactive-centre loop into beta sheet A, thereby abolishing the, ability of the serpin to irreversibly inactivate its target enzyme. The, characterisation of the two binding sites for the peptide inhibitor, provides a solid foundation for computer-aided design of novel, low, molecular weight PAI-1 inhibitors.
DiseaseDisease
Known diseases associated with this structure: Hemorrhagic diathesis due to PAI1 deficiency OMIM:[173360], Thrombophilia due to excessive plasminogen activator inhibitor OMIM:[173360]
About this StructureAbout this Structure
1A7C is a Single protein structure of sequence from Homo sapiens with as ligand. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Interfering with the inhibitory mechanism of serpins: crystal structure of a complex formed between cleaved plasminogen activator inhibitor type 1 and a reactive-centre loop peptide., Xue Y, Bjorquist P, Inghardt T, Linschoten M, Musil D, Sjolin L, Deinum J, Structure. 1998 May 15;6(5):627-36. PMID:9634700
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