What is the total number of protons Complex IV transfers to the Pside?

In the context of cellular respiration and the electron transport chain, Complex IV, known as cytochrome c oxidase, plays a crucial role in the transfer of electrons and the creation of a proton gradient across the inner mitochondrial membrane.

Complex IV accepts electrons from reduced cytochrome c and facilitates the transfer of these electrons to molecular oxygen, which is the terminal electron acceptor that is reduced to form water. During this process, Complex IV also actively pumps protons from the mitochondrial matrix into the intermembrane space, contributing to the proton gradient that is essential for ATP synthesis.

The total number of protons that Complex IV transfers to the P-side, or the intermembrane space, is four. This is a key aspect of chemiosmosis, where the accumulated protons in the intermembrane space create a proton motive force that drives ATP synthase to convert ADP and inorganic phosphate into ATP.

Thus, the total yield of four protons exported per two electrons transferred to oxygen through Complex IV accurately reflects its contribution to the proton gradient necessary for ATP production.