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PDBsum entry 1skc
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Glycogen phosphorylase
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PDB id
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1skc
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References listed in PDB file
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Key reference
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Title
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Activator anion binding site in pyridoxal phosphorylase b: the binding of phosphite, Phosphate, And fluorophosphate in the crystal.
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Authors
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N.G.Oikonomakos,
S.E.Zographos,
K.E.Tsitsanou,
L.N.Johnson,
K.R.Acharya.
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Ref.
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Protein Sci, 1996,
5,
2416-2428.
[DOI no: ]
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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
perfect match.
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Abstract
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It has been established that phosphate analogues can activate glycogen
phosphorylase reconstituted with pyridoxal in place of the natural cofactor
pyridoxal 5'-phosphate (Change YC. McCalmont T, Graves DJ. 1983. Biochemistry
22:4987-4993). Pyridoxal phosphorylase b has been studied by kinetic,
ultracentrifugation, and X-ray crystallographic experiments. In solution, the
catalytically active species of pyridoxal phosphorylase b adopts a conformation
that is more R-state-like than that of native phosphorylase b, but an inactive
dimeric species of the enzyme can be stabilized by activator phosphite in
combination with the T-state inhibitor glucose. Co-crystals of pyridoxal
phosphorylase b complexed with either phosphite, phosphate, or fluorophosphate,
the inhibitor glucose, and the weak activator IMP were grown in space group
P4(3)2(1)2, with native-like unit cell dimensions, and the structures of the
complexes have been refined to give crystallographic R factors of 18.5-19.2%,
for data between 8 and 2.4 A resolution. The anions bind tightly at the
catalytic site in a similar but not identical position to that occupied by the
cofactor 5'-phosphate group in the native enzyme (phosphorus to phosphorus atoms
distance = 1.2 A). The structural results show that the structures of the
pyridoxal phosphorylase b-anion-glucose-IMP complexes are overall similar to the
glucose complex of native T-state phosphorylase b. Structural comparisons
suggest that the bound anions, in the position observed in the crystal, might
have a structural role for effective catalysis.
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