--- title: "Triose phosphate isomerase Template – Chemistry Diagram | MolDraw" url: https://www.moldraw.com/templates/enzyme-tpi-enediol/ description: "Triose phosphate isomerase template: Glu165 removes the pro-R proton from C1 of dihydroxyacetone phosphate, His95 protonates the carbonyl oxygen to give the…" lang: en publisher: Scidart Academy generated: 2026-11-13 --- [MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Biochemistry](https://www.moldraw.com/templates/biochemistry/) › Triose phosphate isomerase [Biochemistry](https://www.moldraw.com/templates/biochemistry/)Premium # Triose phosphate isomerase template ![Triose phosphate isomerase template: Glu165 removes the pro-R proton from C1 of dihydroxyacetone phosphate, His95 protonates the carbonyl oxygen to give the cis-enediol, His95 then takes the O1 proton back and Glu165 delivers a proton to C2, giving D-glyceraldehyde 3-phosphate.](https://www.moldraw.com/templates/enzyme-tpi-enediol.webp) [Edit in MolDraw](https://www.moldraw.com/)Download with Pro Premium template. Preview and edit it free in MolDraw; downloading and exporting it is part of [MolDraw Pro](https://www.moldraw.com/pricing). Glu165 removes the pro-R proton from C1 of dihydroxyacetone phosphate, His95 protonates the carbonyl oxygen to give the cis-enediol, His95 then takes the O1 proton back and Glu165 delivers a proton to C2, giving D-glyceraldehyde 3-phosphate. ## Mechanism step by step Glu165 moves a proton from C1 to C2 while His95 shuttles one between the oxygens, through an enediol intermediate 1. **Glu165 removes H from C1** – An enediolate forms; the O⁻ is held by Lys12 and His95 2. **His95 protonates O2** – Neutral His95 acts as the acid: the cis-enediol and an imidazolate 3. **His95 takes the O1 proton** – The other enediolate 4. **Glu165 protonates C2** – C=O forms at C1: D-glyceraldehyde 3-phosphate ## Key points - TPI is a "perfect" enzyme: kcat/KM ≈ 10⁸ M⁻¹ s⁻¹, so the rate is limited by diffusion (Albery & Knowles 1977). - Equilibrium favours DHAP (about 96:4), but aldolase, then GAP dehydrogenase, keeps pulling GAP away, so both trioses go down glycolysis. - A loop (residues 166–176) closes over the phosphate and keeps the enediol from losing phosphate to give toxic methylglyoxal. - Phosphoglycolohydroxamate and 2-phosphoglycolate, enediol(ate) analogues, are tight-binding transition-state-analogue inhibitors. Drawn with 144 atoms, 15 arrows, 8 shapes – every one editable in MolDraw. ## Sources - [Nelson & Cox, Lehninger Principles of Biochemistry, 8th ed., 2021, ch. 14](https://openlibrary.org/isbn/9781319228002) Textbook - [Berg, Tymoczko, Gatto & Stryer, Biochemistry, 9th ed., 2019, ch. 16](https://openlibrary.org/isbn/9781319114657) Textbook - [Albery & Knowles, Angew. Chem. Int. Ed. Engl. 1977, 16, 285](https://doi.org/10.1002/anie.197702851) Original paper ## How to use this template 1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor. 2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need. 3. Add your own structures, arrows and text next to it, or combine several templates on one page. 4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers. ## Frequently asked questions ### Is the Triose phosphate isomerase template free? You can preview the Triose phosphate isomerase template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates. ### Can I edit the Triose phosphate isomerase template? Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it. ### Is the chemistry checked? Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page. ### Are the biochemical pathways drawn with structures? Yes. 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