摘要
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Inositol 1,3,4,5,6-pentakisphosphate kinase (IP<sub>5</sub> 2-K) is an enzyme involved in inositol metabolism that synthesizes IP<sub>6</sub> (inositol 1,2,3,4,5,6-hexakisphosphate) from inositol 1,3,4,5,6-pentakisphosphate (IP<su...
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Inositol 1,3,4,5,6-pentakisphosphate kinase (IP<sub>5</sub> 2-K) is an enzyme involved in inositol metabolism that synthesizes IP<sub>6</sub> (inositol 1,2,3,4,5,6-hexakisphosphate) from inositol 1,3,4,5,6-pentakisphosphate (IP<sub>5</sub>) and ATP. IP<sub>6</sub> is the major phosphorus reserve in plants, while in mammals it is involved in multiple cellular events such as DNA editing and chromatin remodelling. In addition, IP<sub>6</sub> is the precursor of other highly phosphorylated inositols which also play highly relevant roles. IP<sub>5</sub> 2-K is the only enzyme that phosphorylates the 2-OH axial position of the inositide and understanding its molecular mechanism of substrate specificity is of great interest in cell biology. IP<sub>5</sub> 2-K from Arabidopsis thaliana has been expressed in Escherichia coli as two different fusion proteins and purified. Both protein preparations yielded crystals of different quality, always in the presence of IP<sub>6</sub>. The best crystals obtained for X-ray crystallographic analysis belonged to space group P2<sub>1</sub>2<sub>1</sub>2<sub>1</sub>, with unit-cell parameters a = 58.124, b = 113.591, c = 142.478 Å. Several diffraction data sets were collected for the native enzyme and two heavy-atom derivatives using a synchrotron source.
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