Protonophore

A protonophore, also known as a proton translocator, is an ionophore that moves protons across lipid bilayers. This would otherwise not occur as protons cations (H⁺) have positive charge and hydrophilic properties, making them unable to cross without a channel or transporter in the form of a protonophore. Protonophores are generally aromatic compounds with a negative charge, that are both hydrophobic and capable of distributing the negative charge over a number of atoms by π-orbitals which delocalize a proton's charge when it attaches to the molecule. Both the neutral and the charged protonophore can diffuse across the lipid bilayer by passive diffusion and simultaneously facilitate proton transport. Protonophores uncouple oxidative phosphorylation via a decrease in the membrane potential of the inner membrane of mitochondria. They stimulate mitochondria respiration and heat production. Protonophores (uncouplers) are often used in biochemistry research to help explore the bioenergetics of chemiosmotic and other membrane transport processes.

Representative protonophores include:

The facilitated transport of protons across the biological membrane by protonophore is achieved as follows.

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