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PDBsum entry 2skc
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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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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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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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