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Reaction-cycle structures
Human PGK closed ternary states 2XE7 — 3-PG + ADP reaction cycle (Zerrad M et al., J Biol Chem 2011, PMID:21349853).
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① Substrates across the cleft
[schematic] The two hinged domains close around 1,3-BPG (schematic C1 acyl-phosphate on the 3-PG slot) and ADP; an arginine/ladder network and Mg²⁺ lock the substrates with the ADP β-P ~4 Å from the acyl phosphate, in-line for attack.
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② Transfer → 3-PG + ATP (payoff)
[schematic] The ADP β-oxygen attacks the 1,3-BPG acyl-phosphate in-line (inversion), handing the C1 phosphate to ADP — the first substrate-level ATP generation; 3-PG is the leaving group (snaps to the crystal 3-PG pose).
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③ Products leave
[schematic] ATP and 3-PG dissociate as the domains reopen — the first net ATP harvest of glycolysis.
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Sequence
DNA/gene NCBI Gene 5230 · protein UniProt P00558
› Backbones and ligand poses are taken directly from the listed PDB entries,
superposed into one common frame. Where no crystalline state exists for a step
(e.g., Michaelis geometry), the pose is drawn schematically using PubChem 3D
geometries and is labeled as such in the narration.