tilakoidruumi

The thylakoid lumen, also known as the thylakoid lumen or thylakoid space, is the internal compartment enclosed by the thylakoid membranes within chloroplasts. These membranes are the sites of the light-dependent reactions of photosynthesis. The thylakoid lumen is a distinct aqueous space that plays a crucial role in energy transduction. During the light-dependent reactions, protons (H+) are actively pumped from the stroma into the thylakoid lumen by the electron transport chain. This process, driven by the energy absorbed from sunlight, leads to a significant accumulation of protons within the lumen, creating a proton gradient across the thylakoid membrane. This proton gradient represents a form of stored potential energy. The protons then flow back into the stroma through an enzyme called ATP synthase, a process known as chemiosmosis. This flow of protons powers the synthesis of ATP, the main energy currency of the cell. The thylakoid lumen also contains various enzymes and proteins involved in photophosphorylation and other aspects of photosynthesis. Its acidic pH, a consequence of proton accumulation, is critical for the proper functioning of ATP synthase.