The compound Nonactin binds to which metal ion?  

CONCEPT:

Nonactin as an Ionophore

• Nonactin is a type of ionophore, which is a chemical compound that facilitates the transport of ions across lipid membranes.
• It is known for its selective binding to specific metal ions, particularly potassium ions (K⁺).
• The structure of Nonactin contains a cyclic arrangement that forms a cavity suitable for binding K⁺ ions due to their size and charge.
• This selective binding is due to the size compatibility of the K⁺ ion with the cavity created by the cyclic Nonactin molecule, as well as favorable interactions between the ion and the oxygen atoms in Nonactin.

EXPLANATION:

• Nonactin exhibits high specificity for K⁺ ions over other metal ions like Na⁺, Mg²⁺, and Ca²⁺.
• This specificity is crucial for its biological role, especially in processes like transporting potassium ions across membranes in cells.
• Other ions like Na⁺ are smaller and do not fit as well into the cavity of Nonactin, while larger divalent ions like Mg²⁺ and Ca²⁺ are less compatible with the binding site due to their charge and hydration characteristics.
• Therefore, Nonactin is most effective in binding and transporting K⁺ ions, making option 1 the correct answer.

Therefore, the compound Nonactin specifically binds to potassium ions (K⁺).