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How does carbon dioxide move between dissolved forms on its way out?
Carbonic anhydrase helps connect carbon dioxide with bicarbonate in the chemistry of breathing.
Sources for this view
The enzyme catalyzes the reversible interconversion CO₂ + H₂O ⇌ HCO₃⁻ + H⁺. This permits rapid changes between chemical forms as carbon dioxide is transported and released. It does not create or destroy the carbon atom.
Sources for this view
Explore the model (optional)
EXPLORE THE MODEL
A deposited zinc site
Select a site to identify its entry, residue and atom. In the overlay, smaller purple wireframes represent the apo record; larger chemical-color wireframes show the native record. Click repeatedly to cycle overlapping sites, or use the site selector.
What this representation means
Coordinates are refined crystallographic models, not direct photographs or trajectories. PDB HOH oxygen has no modeled hydrogen atoms here; water/hydroxide protonation is not established from these coordinates alone. Protein side-chain bonds may be inferred by standard HIS connectivity, but only the four explicitly listed Zn contacts are coordination evidence. No metal atom is constructed for the apo record. A reference-location marker, if used, must be labeled ghost/reference. Native and aligned apo coordinates share one fixed display frame. Overlaying the records does not show motion, a reaction path or a time sequence. Purple apo atoms are deposited atoms; no apo zinc is constructed.
- Selected entries
- 2CBA
- Alignment
- 258 matched Cα atoms · RMSD 0.098 Å
- Zn contacts in 2CBA
- His94 NE2 2.101 Å · His96 NE2 2.116 Å · His119 ND1 2.107 Å
- Water O → Zn in 2CBA
- 2.052 Å
- 2CBE water O displacement after alignment
- 0.869 Å from native water O; not a trajectory
- Resolution
- 2CBA 1.54 Å · 2CBE 1.82 Å
Select an atom or residue site in the model. Native coordinates include zinc and its nearby ligands. The apo record is independently deposited and aligned on matched backbone atoms; removing the zinc from a picture would not generate those observations.
What this model can establish
Selected histidine residues and a water oxygen from deposited crystal structures. Connectors mark coordination or residue bonds, not a reaction movie. Hydrogen positions, motion and catalytic rates are not inferred.
Optional: check your understanding
MAKE THE CONNECTION
Which role is consistent with the balanced reaction?