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Title
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Three-dimensional structure of thymidine phosphorylase from Escherichia coli at 2.8 A resolution.
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Authors
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M.R.Walter,
W.J.Cook,
L.B.Cole,
S.A.Short,
G.W.Koszalka,
T.A.Krenitsky,
S.E.Ealick.
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Ref.
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J Biol Chem, 1990,
265,
14016-14022.
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PubMed id
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Abstract
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The three-dimensional structure of thymidine phosphorylase from Escherichia coli
has been determined at 2.8 A resolution using multiple-isomorphous-replacement
techniques. The amino acid sequence deduced from the deoA DNA sequence is also
reported. Thymidine phosphorylase exists in the crystal as an S-shaped dimer in
which the subunits are related by a crystallographic 2-fold axis. Each subunit
is composed of a small alpha-helical domain of six helices and a large
alpha/beta domain. The alpha/beta domain includes a six-stranded mixed
beta-sheet and a four-stranded antiparallel beta-sheet. The active site has been
identified by difference Fourier analyses of the binding of thymine and
thymidine and lies in a cavity between the small and large domains. The central
beta-sheet is splayed open to accommodate a putative phosphate-binding site
which is probably occupied by a sulfate ion in the crystal.
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