1qm5
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Phosphorylases are key enzymes of carbohydrate metabolism. Structural, studies have provided explanations for almost all features of control and, substrate recognition of phosphorylase but one question remains, unanswered. How does phosphorylase recognize and cleave an oligosaccharide, substrate? To answer this question we turned to the Escherichia coli, maltodextrin phosphorylase (MalP), a non-regulatory phosphorylase that, shares similar kinetic and catalytic properties with the mammalian, glycogen phosphorylase. The crystal structures of three, MalP-oligosaccharide complexes are reported: the binary complex of MalP, with the natural substrate, maltopentaose (G5); the binary complex with, the thio-oligosaccharide, 4-S-alpha-D-glucopyranosyl-4-thiomaltotetraose, (GSG4), both at 2.9 A ... | + | Phosphorylases are key enzymes of carbohydrate metabolism. Structural, studies have provided explanations for almost all features of control and, substrate recognition of phosphorylase but one question remains, unanswered. How does phosphorylase recognize and cleave an oligosaccharide, substrate? To answer this question we turned to the Escherichia coli, maltodextrin phosphorylase (MalP), a non-regulatory phosphorylase that, shares similar kinetic and catalytic properties with the mammalian, glycogen phosphorylase. The crystal structures of three, MalP-oligosaccharide complexes are reported: the binary complex of MalP, with the natural substrate, maltopentaose (G5); the binary complex with, the thio-oligosaccharide, 4-S-alpha-D-glucopyranosyl-4-thiomaltotetraose, (GSG4), both at 2.9 A resolution; and the 2.1 A resolution ternary complex, of MalP with thio-oligosaccharide and phosphate (GSG4-P). The results show, a pentasaccharide bound across the catalytic site of MalP with sugars, occupying sub-sites -1 to +4. Binding of GSG4 is identical to the natural, pentasaccharide, indicating that the inactive thio compound is a close, mimic of the natural substrate. The ternary MalP-GSG4-P complex shows the, phosphate group poised to attack the glycosidic bond and promote, phosphorolysis. In all three complexes the pentasaccharide exhibits an, altered conformation across sub-sites -1 and +1, the site of catalysis, from the preferred conformation for alpha(1-4)-linked glucosyl polymers. |
==About this Structure== | ==About this Structure== | ||
| - | 1QM5 is a | + | 1QM5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with GLC, PO4 and PLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phosphorylase Phosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.1 2.4.1.1] Structure known Active Sites: CAA and CAB. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QM5 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: thio-oligosaccharide]] | [[Category: thio-oligosaccharide]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 15:30:03 2007'' |
Revision as of 13:24, 5 November 2007
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PHOSPHORYLASE RECOGNITION AND PHOSPHORYLYSIS OF ITS OLIGOSACCHARIDE SUBSTRATE: ANSWERS TO A LONG OUTSTANDING QUESTION
Overview
Phosphorylases are key enzymes of carbohydrate metabolism. Structural, studies have provided explanations for almost all features of control and, substrate recognition of phosphorylase but one question remains, unanswered. How does phosphorylase recognize and cleave an oligosaccharide, substrate? To answer this question we turned to the Escherichia coli, maltodextrin phosphorylase (MalP), a non-regulatory phosphorylase that, shares similar kinetic and catalytic properties with the mammalian, glycogen phosphorylase. The crystal structures of three, MalP-oligosaccharide complexes are reported: the binary complex of MalP, with the natural substrate, maltopentaose (G5); the binary complex with, the thio-oligosaccharide, 4-S-alpha-D-glucopyranosyl-4-thiomaltotetraose, (GSG4), both at 2.9 A resolution; and the 2.1 A resolution ternary complex, of MalP with thio-oligosaccharide and phosphate (GSG4-P). The results show, a pentasaccharide bound across the catalytic site of MalP with sugars, occupying sub-sites -1 to +4. Binding of GSG4 is identical to the natural, pentasaccharide, indicating that the inactive thio compound is a close, mimic of the natural substrate. The ternary MalP-GSG4-P complex shows the, phosphate group poised to attack the glycosidic bond and promote, phosphorolysis. In all three complexes the pentasaccharide exhibits an, altered conformation across sub-sites -1 and +1, the site of catalysis, from the preferred conformation for alpha(1-4)-linked glucosyl polymers.
About this Structure
1QM5 is a Single protein structure of sequence from Escherichia coli with GLC, PO4 and PLP as ligands. Active as Phosphorylase, with EC number 2.4.1.1 Structure known Active Sites: CAA and CAB. Full crystallographic information is available from OCA.
Reference
Phosphorylase recognition and phosphorolysis of its oligosaccharide substrate: answers to a long outstanding question., Watson KA, McCleverty C, Geremia S, Cottaz S, Driguez H, Johnson LN, EMBO J. 1999 Sep 1;18(17):4619-32. PMID:10469642
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