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PDBsum entry 2rdl
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Hydrolase/hydrolase inhibitor
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PDB id
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2rdl
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References listed in PDB file
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Key reference
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Title
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Structural basis for elastolytic substrate specificity in rodent alpha-Chymases.
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Authors
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J.Kervinen,
M.Abad,
C.Crysler,
M.Kolpak,
A.D.Mahan,
J.A.Masucci,
S.Bayoumy,
M.D.Cummings,
X.Yao,
M.Olson,
L.De garavilla,
L.Kuo,
I.Deckman,
J.Spurlino.
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Ref.
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J Biol Chem, 2008,
283,
427-436.
[DOI no: ]
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PubMed id
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Abstract
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Divergence of substrate specificity within the context of a common structural
framework represents an important mechanism by which new enzyme activity
naturally evolves. We present enzymological and x-ray structural data for
hamster chymase-2 (HAM2) that provides a detailed explanation for the unusual
hydrolytic specificity of this rodent alpha-chymase. In enzymatic
characterization, hamster chymase-1 (HAM1) showed typical chymase proteolytic
activity. In contrast, HAM2 exhibited atypical substrate specificity, cleaving
on the carboxyl side of the P1 substrate residues Ala and Val, characteristic of
elastolytic rather than chymotryptic specificity. The 2.5-A resolution crystal
structure of HAM2 complexed to the peptidyl inhibitor
MeOSuc-Ala-Ala-Pro-Ala-chloromethylketone revealed a narrow and shallow S1
substrate binding pocket that accommodated only a small hydrophobic residue
(e.g. Ala or Val). The different substrate specificities of HAM2 and HAM1 are
explained by changes in four S1 substrate site residues (positions 189, 190,
216, and 226). Of these, Asn(189), Val(190), and Val(216) form an easily
identifiable triplet in all known rodent alpha-chymases that can be used to
predict elastolytic specificity for novel chymase-like sequences. Phylogenetic
comparison defines guinea pig and rabbit chymases as the closest orthologs to
rodent alpha-chymases.
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Figure 4.
FIGURE 4. Structural analysis of the catalytic cleft. A,
accessible surface of molecules A (white-blue-red) and B
(green-blue-red) in the asymmetric unit with
MeOSuc-Ala-Ala-Pro-Ala-CMK shown for molecule A. B,
semitransparent surface representation of the catalytic cleft of
HAM2. The stick model in color-by-atom denotes
MeOSuc-Ala-Ala-Pro-Ala-CMK bound to HAM2.
Suc-Ala-Ala-Pro-Phe-CMK (magenta), covalently bound to the
crystal structure of human chymase (37), is superimposed onto
the HAM2 structure. Molecular figures were prepared with PyMOL
(DeLano Scientific LLC, www.pymol.org).
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Figure 5.
FIGURE 5. Schematic diagram of the hydrogen bond and other
interactions between HAM2 and the inhibitor
MeOSuc-Ala-Ala-Pro-Ala-CMK.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2008,
283,
427-436)
copyright 2008.
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