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PDBsum entry 1gsq
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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-Dimensional structure, Catalytic properties, And evolution of a sigma class glutathione transferase from squid, A progenitor of the lens s-Crystallins of cephalopods.
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Authors
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X.Ji,
E.C.Von rosenvinge,
W.W.Johnson,
S.I.Tomarev,
J.Piatigorsky,
R.N.Armstrong,
G.L.Gilliland.
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Ref.
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Biochemistry, 1995,
34,
5317-5328.
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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 were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
93%.
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Abstract
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The glutathione transferase from squid digestive gland is unique in its very
high catalytic activity toward 1-chloro-2,4-dinitrobenzene and in its ancestral
relationship to the genes encoding the S-crystallins of the lens of cephalopod
eye. The three-dimensional structure of this glutathione transferase in complex
with the product 1-(S-glutathionyl)-2,4-dinitrobenzene (GSDNB) has been solved
by multiple isomorphous replacement techniques at a resolution of 2.4 A. Like
the cytosolic enzymes from vertebrates, the squid protein is a dimer. The
structure is similar in overall topology to the vertebrate enzymes but has a
dimer interface that is unique when compared to all of the vertebrate and
invertebrate structures thus far reported. The active site of the enzyme is very
open, a fact that appears to correlate with the high turnover number (800 s-1 at
pH 6.5) toward 1-chloro-2,4-dinitrobenzene. Both kcat and kcat/KmCDNB exhibit pH
dependencies consistent with a pKa for the thiol of enzyme-bound GSH of 6.3. The
enzyme is not very efficient at catalyzing the addition of GSH to enones and
epoxides. This particular characteristic appears to be due to the lack of an
electrophilic residue at position 106, which is often found in other GSH
transferases. The F106Y mutant enzyme is much improved in catalyzing these
reactions. Comparisons of the primary structure, gene structure, and
three-dimensional structure with class alpha, mu, and pi enzymes support placing
the squid protein in a separate enzyme class, sigma. The unique dimer interface
suggests that the class sigma enzyme diverged from the ancestral precursor prior
to the divergence of the precursor gene for the alpha, mu, and pi classes.
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Secondary reference #1
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Title
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Structure and function of the xenobiotic substrate binding site of a glutathione s-Transferase as revealed by x-Ray crystallographic analysis of product complexes with the diastereomers of 9-(S-Glutathionyl)-10-Hydroxy-9,10-Dihydrophenanthrene.
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Authors
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X.Ji,
W.W.Johnson,
M.A.Sesay,
L.Dickert,
S.M.Prasad,
H.L.Ammon,
R.N.Armstrong,
G.L.Gilliland.
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Ref.
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Biochemistry, 1994,
33,
1043-1052.
[DOI no: ]
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PubMed id
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Secondary reference #2
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Title
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Snapshots along the reaction coordinate of an snar reaction catalyzed by glutathione transferase.
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Authors
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X.Ji,
R.N.Armstrong,
G.L.Gilliland.
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Ref.
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Biochemistry, 1993,
32,
12949-12954.
[DOI no: ]
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PubMed id
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Secondary reference #3
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Title
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The three-Dimensional structure of a glutathione s-Transferase from the mu gene class. Structural analysis of the binary complex of isoenzyme 3-3 and glutathione at 2.2-A resolution.
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Authors
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X.Ji,
P.Zhang,
R.N.Armstrong,
G.L.Gilliland.
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Ref.
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Biochemistry, 1992,
31,
10169-10184.
[DOI no: ]
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PubMed id
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