1djx
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PHOSPHOINOSITIDE-SPECIFIC PHOSPHOLIPASE C-DELTA1 FROM RAT COMPLEXED WITH INOSITOL-1,4,5-TRISPHOSPHATE
OverviewOverview
The crystal structures of various ternary complexes of, phosphoinositide-specific phospholipase C-delta 1 from rat with calcium, and inositol phosphates have been determined at 2.30-2.95 A resolution., The inositol phosphates used in this study mimic the binding of substrates, and the reaction intermediate and include, D-myo-inositol-1,4,5-trisphosphate, D-myo-inositol-2,4, 5-trisphosphate., D-myo-inositol-4,5-bisphosphate, and, D,1-myo-inositol-2-methylene-1,2-cyclicmonophosphonate. The complexes, exhibit an almost invariant mode of binding in the active site, each, fitting edge-on into the active site and interacting with both the enzyme, and the catalytic calcium at the bottom of the active site. Most of the, active site residues do not undergo conformational changes upon binding, either calcium or inositol phosphates. The structures are consistent with, bidentate liganding of the catalytic calcium to the inositol phosphate, intermediate and transition state. The complexes suggest explanations for, substrate preference, pH optima, and ratio of cyclic to acyclic reaction, products. A reaction mechanism is derived that supports general acid/base, catalysis in a sequential mechanism involving a cyclic phosphate, intermediate and rules out a parallel mechanism where acyclic and cyclic, products are simultaneously generated.
About this StructureAbout this Structure
1DJX is a Single protein structure of sequence from Rattus norvegicus with CA, ACT and I3P as ligands. Active as Phosphoinositide phospholipase C, with EC number 3.1.4.11 Full crystallographic information is available from OCA.
ReferenceReference
Structural mapping of the catalytic mechanism for a mammalian phosphoinositide-specific phospholipase C., Essen LO, Perisic O, Katan M, Wu Y, Roberts MF, Williams RL, Biochemistry. 1997 Feb 18;36(7):1704-18. PMID:9048554
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