1rxo
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ACTIVATED SPINACH RUBISCO IN COMPLEX WITH ITS SUBSTRATE RIBULOSE-1,5-BISPHOSPHATE AND CALCIUM
OverviewOverview
The three-dimensional structure of the complex of ribulose, 1,5-bisphosphate carboxylase/oxygenase (rubisco; EC 4.1.1.39) from spinach, with its natural substrate ribulose 1,5-bisphosphate (RuBP) has been, determined both under activating and non-activating conditions by X-ray, crystallography to a resolution of 2.1 A and 2.4 A, respectively. Under, activating conditions, the use of calcium instead of magnesium as the, activator metal ion enabled us to trap the substrate in a stable complex, for crystallographic analysis. Comparison of the structure of the, activated and the non-activated RuBP complexes shows a tighter binding for, the substrate in the non-activated form of the enzyme, in line with, previous solution studies. In the non-activated complex, the substrate, triggers isolation of the active site by inducing movements of flexible, loop regions of the catalytic subunits. In contrast, in the activated, complex the active site remains partly open, probably awaiting the binding, of the gaseous substrate. By inspection of the structures and by, comparison with other complexes of the enzyme we were able to identify a, network of hydrogen bonds that stabilise a closed active site structure, during crucial steps in the reaction. The present structure underlines the, central role of the carbamylated lysine 201 in both activation and, catalysis, and completes available structural information for our proposal, on the mechanism of the enzyme.
About this StructureAbout this Structure
1RXO is a Protein complex structure of sequences from Spinacia oleracea with RUB and CA as ligands. Active as Ribulose-bisphosphate carboxylase, with EC number 4.1.1.39 Structure known Active Sites: ACB, ACE, ACH and ACL. Full crystallographic information is available from OCA.
ReferenceReference
The structure of the complex between rubisco and its natural substrate ribulose 1,5-bisphosphate., Taylor TC, Andersson I, J Mol Biol. 1997 Jan 31;265(4):432-44. PMID:9034362
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