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Title
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Stereochemistry of binding of the tetrapeptide acetyl-Pro-Ala-Pro-Tyr-NH2 to porcine pancreatic elastase. Combined use of two-dimensional transferred nuclear Overhauser enhancement measurements, restrained molecular dynamics, X-ray crystallography and molecular modelling.
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Authors
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G.M.Clore,
A.M.Gronenborn,
G.Carlson,
E.F.Meyer.
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Ref.
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J Mol Biol, 1986,
190,
259-267.
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PubMed id
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Abstract
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A nuclear magnetic resonance study of the conformation of the tetrapeptide
acetyl-Pro-Ala-Pro-Tyr-NH2 bound to porcine pancreatic elastase is presented.
From two-dimensional transferred nuclear Overhauser enhancement measurements, a
set of 23 approximate distance restraints between pairs of bound ligand protons,
indicative of an extended type structure, is derived. The structure of the bound
tetrapeptide is then refined from two different starting structures (an extended
beta-strand and a polyproline helix) by restrained molecular dynamics, in which
the interproton distances are incorporated into the total energy of the system
in the form of effective potentials. Convergence to essentially the same average
restrained dynamics structures is achieved. The refined structures are then
modelled into the active site of elastase by interactive molecular graphics. The
determination of the anchor point of the bound tetrapeptide on the enzyme was
aided by a simultaneous crystallographic study which, despite the fact that only
electron density for a Pro-X dipeptide fragment was visible, enabled both the
approximate position and orientation of binding to be determined. It is found
that the tetrapeptide is bound in the S' binding site in the reverse orientation
found in other serine protease-inhibitor complexes and is stabilized both by
hydrogen-bonding and by van der Waals' interactions.
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