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PDBsum entry 5wxf
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Hydrolase/hydrolase inhibitor
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PDB id
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5wxf
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References listed in PDB file
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Key reference
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Title
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Cleavage of peptidic inhibitors by target protease is caused by peptide conformational transition.
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Authors
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L.Jiang,
E.Oldenburg,
T.Kromann-Hansen,
P.Xu,
J.K.Jensen,
P.A.Andreasen,
M.Huang.
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Ref.
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Biochim Biophys Acta, 2018,
1862,
2017-2023.
[DOI no: ]
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PubMed id
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Note: In the PDB file this reference is
annotated as "TO BE PUBLISHED". The citation details given above have
been manually determined.
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Abstract
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Some peptide sequences can behave as either substrates or inhibitors of serine
proteases. Working with a cyclic peptidic inhibitor of the serine protease
urokinase-type plasminogen activator (uPA), we have now demonstrated a new
mechanism for an inhibitor-to-substrate switch. The peptide, CSWRGLENHAAC
(upain-2), is a competitive inhibitor of human uPA, but is also slowly converted
to a substrate in which the bond between Arg4 and Gly5
(the P1-P1' bond) is cleaved. Substituting the P2 residue Trp3 to an
Ala or substituting the P1 Arg4 residue with
4-guanidino-phenylalanine strongly increased the substrate cleavage rate. We
studied the structural basis for the inhibitor-to-substrate switch by
determining the crystal structures of the various peptide variants in complex
with the catalytic domain of uPA. While the slowly cleaved peptides bound
clearly in inhibitory mode, with the oxyanion hole blocked by the side chain of
the P3' residue Glu7, peptides behaving essentially as substrates
with a much accelerated rate of cleavage was observed to be bound to the enzyme
in substrate mode. Our analysis reveals that the inhibitor-to-substrate switch
was associated with a 7 Å translocation of the P2 residue, and we conclude
that the inhibitor-to-substrate switch of upain-2 is a result of a major
conformational change in the enzyme-bound state of the peptide. This conclusion
is in contrast to findings with so-called standard mechanism inhibitors in which
the inhibitor-to-substrate switch is linked to minor conformational changes in
the backbone of the inhibitory peptide stretch.
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