--- title: "Biotin carboxylation (acetyl-CoA carboxylase) Template | MolDraw" url: https://www.moldraw.com/templates/enzyme-biotin-carboxylation/ description: "Biotin carboxylation (acetyl-CoA carboxylase) template: Bicarbonate attacks the γ-phosphate of ATP to form carboxyphosphate, which gives CO₂ and phosphate…" 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/) › Biotin carboxylation (acetyl-CoA carboxylase) [Biochemistry](https://www.moldraw.com/templates/biochemistry/)Premium # Biotin carboxylation (acetyl-CoA carboxylase) template ![Biotin carboxylation (acetyl-CoA carboxylase) template: Bicarbonate attacks the γ-phosphate of ATP to form carboxyphosphate, which gives CO₂ and phosphate; N1′ of biotin (on a Lys) takes up the CO₂, and in the carboxyltransferase site carboxybiotin releases CO₂ to the enolate of acetyl-CoA, giving malonyl-CoA.](https://www.moldraw.com/templates/enzyme-biotin-carboxylation.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). Bicarbonate attacks the γ-phosphate of ATP to form carboxyphosphate, which gives CO₂ and phosphate; N1′ of biotin (on a Lys) takes up the CO₂, and in the carboxyltransferase site carboxybiotin releases CO₂ to the enolate of acetyl-CoA, giving malonyl-CoA. ## Mechanism step by step ATP activates bicarbonate as carboxyphosphate; biotin carries the CO₂ to acetyl-CoA, giving malonyl-CoA 1. **Carboxyphosphate** – Bicarbonate attacks the γ-phosphorus of ATP (R = adenosine); ADP leaves 2. **CO₂ release** – Carboxyphosphate breaks down to CO₂ and phosphate (drawn as one step) 3. **Carboxybiotin** – Phosphate removes the N1′–H of biotin as N1′ attacks CO₂ 4. **CO₂ leaves biotin** – In the carboxyltransferase site carboxybiotin gives CO₂ and the biotin N1′ anion 5. **Malonyl-CoA** – Biotin N⁻ takes an α-H of acetyl-CoA; the enolate carbon adds to CO₂ (drawn concerted) ## Key points - Biotin is bound by an amide to a Lys ε-amino group of the biotin carboxyl carrier protein; the long arm swings CO₂ between the two active sites. - ATP is spent to activate HCO₃⁻: carboxyphosphate is a mixed anhydride, and N1′-carboxybiotin stores the "activated CO₂" (Lane & Lynen 1963). - Acetyl-CoA carboxylase makes malonyl-CoA, the committed step of fatty-acid synthesis; citrate activates it and AMPK phosphorylation inhibits it. - Pyruvate carboxylase and propionyl-CoA carboxylase use the same biotin chemistry; raw egg white avidin binds biotin and blocks them. Drawn with 199 atoms, 19 arrows, 8 shapes – every one editable in MolDraw. ## Sources - [Nelson & Cox, Lehninger Principles of Biochemistry, 8th ed., 2021, ch. 21](https://openlibrary.org/isbn/9781319228002) Textbook - [Berg, Tymoczko, Gatto & Stryer, Biochemistry, 9th ed., 2019, ch. 22](https://openlibrary.org/isbn/9781319114657) Textbook - [Lane & Lynen, Proc. Natl. Acad. Sci. USA 1963, 49, 379](https://doi.org/10.1073/pnas.49.3.379) 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 Biotin carboxylation (acetyl-CoA carboxylase) template free? You can preview the Biotin carboxylation (acetyl-CoA carboxylase) 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 Biotin carboxylation (acetyl-CoA carboxylase) 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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