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PDBsum entry 1gc4
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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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Substrate recognition mechanism of thermophilic dual-Substrate enzyme.
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Authors
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H.Ura,
T.Nakai,
S.I.Kawaguchi,
I.Miyahara,
K.Hirotsu,
S.Kuramitsu.
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Ref.
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J Biochem (tokyo), 2001,
130,
89-98.
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PubMed id
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Abstract
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Aspartate aminotransferase from an extremely thermophilic bacterium, Thermus
thermophilus HB8 (ttAspAT), has been believed to be specific for an acidic
substrate. However, stepwise introduction of mutations in the active-site
residues finally changed its substrate specificity to that of a dual-substrate
enzyme. The final mutant, [S15D, T17V, K109S, S292R] ttAspAT, is active toward
both acidic and hydrophobic substrates. During the course of stepwise mutation,
the activities toward acidic and hydrophobic substrates changed independently.
The introduction of a mobile Arg292* residue into ttAspAT was the key step in
the change to a "dual-substrate" enzyme. The substrate recognition mechanism of
this thermostable "dual-substrate" enzyme was confirmed by X-ray
crystallography. This work together with previous studies on various enzymes
suggest that this unique "dual-substrate recognition" mechanism is a feature of
not only aminotransferases but also other enzymes.
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Secondary reference #1
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Title
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Structure of thermus thermophilus hb8 aspartate aminotransferase and its complex with maleate.
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Authors
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T.Nakai,
K.Okada,
S.Akutsu,
I.Miyahara,
S.Kawaguchi,
R.Kato,
S.Kuramitsu,
K.Hirotsu.
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Ref.
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Biochemistry, 1999,
38,
2413-2424.
[DOI no: ]
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PubMed id
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Secondary reference #2
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Title
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The novel substrate recognition mechanism utilized by aspartate aminotransferase of the extreme thermophile thermus thermophilus hb8.
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Authors
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Y.Nobe,
S.Kawaguchi,
H.Ura,
T.Nakai,
K.Hirotsu,
R.Kato,
S.Kuramitsu.
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Ref.
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J Biol Chem, 1998,
273,
29554-29564.
[DOI no: ]
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PubMed id
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Figure 1.
Fig. 1. Structure of the active site of aspartate
aminotransferase. a, T. thermophilus AspAT in the substrate-free
form (27). b, E. coli AspAT in the substrate-free form (22). c,
E. coli AspAT complexed with 2-methylaspartate, acidic substrate
analog (22). Single letter codes are used for amino acid
residues.
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Figure 3.
Fig. 3. Circular dichroism spectra of wild-type AspAT.
PLP form (solid line) and PMP form (dotted line) are shown. The
ordinate shows molar ellipticity ([  ][M]).
Conditions: 50 mM HEPES, 100 mM KCl, 10 µM enzyme, pH 8.0,
and 25 °C
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The above figures are
reproduced from the cited reference
with permission from the ASBMB
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Secondary reference #3
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Title
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An aspartate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus hb8.
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Authors
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A.Okamoto,
R.Kato,
R.Masui,
A.Yamagishi,
T.Oshima,
S.Kuramitsu.
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Ref.
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J Biochem (tokyo), 1996,
119,
135-144.
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PubMed id
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