-
Classic structure
Chicken TPI 1TIM — first TPI structure (Banner DW, Bloomer AC, Petsko GA et al., Biochem Biophys Res Commun 1976, PMID:985462). Human TPI >90% identical. The Edman-bound Michaelis/intermediate complexes are from Lolis E & Petsko GA, Biochemistry 1990, 2YPI (a separate TPI structure).
-
① DHAP docks beside Glu165
[schematic] DHAP binds with its C1 adjacent to the catalytic Glu165 (general base) that will abstract the pro-R proton; the flexible loop caps the pocket (PubChem geometry docked, marked schematic).
-
② Enediolate intermediate
[schematic] Proton abstraction gives the cis-enediol(ate), stabilized by Lys13 and His95; the transition-state-analog inhibitor phosphoglycolohydroxamate (PGH) mimics this state — basis for TPI as a "kinetically perfect" enzyme.
-
③ Reprotonation → G3P out
[schematic] His95 donates H⁺ to C2 and Glu165 returns H⁺ to C1 as the carbonyl moves C2→C1, isomerizing DHAP to G3P (reversible, near-diffusion-limit turnover).
-
Sequence
DNA/gene NCBI Gene 7167 · protein UniProt P60174
› 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.