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PDBsum entry 1ee3
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Three high-Resolution crystal structures of cadmium-Substituted carboxypeptidase a provide insight into the enzymatic function.
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Authors
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F.Jensen,
T.Bukrinsky,
J.Bjerrum,
S.Larsen.
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Ref.
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J Biol Inorg Chem, 2002,
7,
490-499.
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PubMed id
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Abstract
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Three high-resolution crystal structures of Cd(II)-substituted carboxypeptidase
A (CPA) have been determined by X-ray diffraction from crystals prepared in
three different buffer systems to assess the effect of pH and ionic strength on
the Cd(II) coordination geometry. All crystallize in the space group P2(1) with
identical cell dimensions. Cd-CPA(7.5): Cd(II)-substituted CPA prepared at pH
7.5 with [Cl(-)]=2 mM determined to 1.70 A resolution ( R=17.4% and
R(free)=19.8%); Cd-CPA(5.5): Cd(II)-substituted CPA prepared at pH 5.5 with
[Cl(-)]=2 mM to 2.00 A resolution ( R=16.1% and R(free)=18.6%); Cd-CPA(7.5)-Cl:
Cd(II)-substituted CPA prepared at pH 7.5 with [Cl(-)]=250 mM to 1.76 A
resolution ( R=16.7% and R(free)=17.8%). No noticeable structural changes were
observed between the three structures. Two water molecules coordinate to Cd(II),
in contrast to the single water molecule coordinating to Zn(II) in the Zn-CPA
structure. No binding sites for anions could be identified, even in the
structure with a high concentration of chloride ions. It is suggested that the
anion inhibition is due to weak outer-sphere association of Cl(-) ions at
several binding sites, shielding the strong positive charge distribution at the
surface of the protein near the active site. Based on structural data and a
sequence alignment of 18 non-redundant carboxypeptidases, a more elaborate
version of the earlier reaction model is proposed that also addresses the
transport of water to and from the active site. Conserved residues whose
function was not addressed previously delineate the proposed pathways used in
the transport of water during catalysis.
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Secondary reference #1
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Title
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Native carboxypeptidase a in a new crystal environment reveals a different conformation of the important tyrosine 248.
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Authors
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J.T.Bukrinsky,
M.J.Bjerrum,
A.Kadziola.
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Ref.
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Biochemistry, 1998,
37,
16555-16564.
[DOI no: ]
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PubMed id
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Secondary reference #2
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Title
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Carboxypeptidase a: native, Zinc-Removed and mercury-Replaced forms.
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Authors
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H.M.Greenblatt,
H.Feinberg,
P.A.Tucker,
G.Shoham.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 1998,
54,
289-305.
[DOI no: ]
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PubMed id
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Figure 12.
Figure 12 Active site of Hg-CPA, showing Tris molecule bound to
Hg-CPA and another cation (labelled ION) bound to Glu270. The
distance between the cation and Glu270 O  2
is 2.5 Å, and to Glu270 O 1
is 3.5 Å. The distances of the Tris hydroxyl groups to various
side chains in the active site are as follows: to Tyr198 N, 2.5
Å; to Arg71 N  2,
2.8 Å; to Tyr248 O ,
3.5 Å.
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Figure 14.
Figure 14 Plot of R factor versus resolution (PROLSQ refinement)
for two data sets from the DIP-100 (apo-CPA and Hg-CPA), and the
native CPA data sets from the R-AXIS (monochromator).
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The above figures are
reproduced from the cited reference
with permission from the IUCr
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Secondary reference #3
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Title
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Structure and dynamics of the metal site of cadmium-Substituted carboxypeptidase a in solution and crystalline states and under steady-State peptide hydrolysis.
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Authors
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R.Bauer,
E.Danielsen,
L.Hemmingsen,
M.V.Sorensen,
J.Ulstrup,
E.P.Friis,
D.S.Auld,
M.J.Bjerrum.
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Ref.
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Biochemistry, 1997,
36,
11514-11524.
[DOI no: ]
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PubMed id
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